SR-15+
TIME CODE DISTRIPALYZER
A Distributor, a Stripper and an Analyzer Operation Manual
Software version 3.05 BRAINSTORM
...Intelligent Solutions For The Recording Studio ELECTRONICS, INC. SR-15+ TIME CODE DISTRIPALYZER OPERATION MANUAL BRAINSTORM ELECTRONICS, INC. Release Date: June 1994 1
INPUT
DISTRIBUTOR / RESHAPER 1
RESET
Code Vid Ø 2
CODE ANALYZER
TONE STRIPPER
Sec Fr 4
POWER 7 8 9 10 11 12
14 16 20 21 AUX I/O
2
User
Hr Min 3
READER
ASCII
Color Fr.
Code Video Mains 4
Square Sine 5 A Rear
SMPTE Square EBU (25µs) (1µs) (50µs) B Front I O
BRAINSTORM
ELECTRONICS, INC. SR-15+ TIME CODE DISTRIPALYZER
Signal In Good Code BEEPER
Fr/Sec
Drop Fr. Video Code Hz COUNTER INPUT B OUTPUT 5 INPUT SELECT OUTPUT RISE TIME OUTPUT LEVEL (Front Panel) Off
Code
Tone in Tone out On
Frame Rate / Frequency SOURCE SELECT OUTPUT LEVEL OUTPUT WAVEFORM 3 5 6 13 15 17 18 19 22 23 24 25 26 27 Aux I/O Distributor 1. Input B: Auxiliary time code input, for easy front panel access. 2. Output 5: Auxiliary time code output, for easy front panel access. 22. Drop Frame LED: On solid for drop frame code; blinks mostly on for missing DF flag (bit 10); blinks mostly off for false DF flag; off for non-drop. Input Section Analyzer 6. Rise Time Switch: Changes the waveform of all 5 reshaped time code outputs: SMPTE = 25µsec, square wave = 1µsec and EBU = 50 µsec. 7. Output Level (7-11): Adjusts the level of each reshaped output individually from full off to +12dbU. 18. Fr/Sec LED: On when 4 digit display counts frame rate. 19. Hz LED: On when 4 digit display counts frequency. 20. ASCII LED: On when ASCII flags are set. On means User Bits are ASCII; off ,User Bits are Hex. 21. Color Frame LED: On when Color flag is set (bit 11 ); off when flag is not set. 16. Reader (8 digit display): Reads time code, user bits or video phase; identifies the error type and the faulty address. 17. Counter (4 digit display): Reads the frame rate (fr/sec) of the incoming time code or the frequency (hz) of Tone in or Tone out. 23. Video Code LED: On solid if code is synchronous and in phase with video; blinks mostly on if code is out of phase; blinks mostly off if code is drifting; off if no video is present. 3. Input Select: This switch determines which input is active (front or rear). 4. Signal In LED: Lights up when signal is present at the selected input. Any signal above -30db lights this LED. 5. Good Code LED: Lights up when valid code is present at the selected input; blinks off momentarily if a "Fatal" time code error is detected. 12. Reset Switch: Push button to reset SR-15+ or clear displays. 13. Beeper switch: turns beeper off. 14. Reader Select: Selects the mode of the 8 digit display: Time code/ User bits/ Video ø. 15. Counter Select: Selects the input and the mode of the 4 digit display : Code / Tone in / Tone out. Stripper Power 27. Power Switch: Turns power on or off 24. Source Select: Selects the input of the Stripper: Code / Video / AC Mains. 25. Output Level: Adjusts the Strippers output level from full off to +12dbU 26. Output Waveform: Determines the waveform of the stripped tone: Square wave / Sine wave. Isolated COLOR ID VIDEO REFERENCE
(Optional) VID OUT
R Grounded RELAY OUT/IN
T S TONE OUT OUTPUT 4 OUTPUT 3 OUTPUT 2 OUTPUT 1 INPUT A 115 Vac Iso Grnd Input
1 2 3 4 5 6 7 8 XLR Pins: 1=G / 2=H / 3=L Fuse, Slo-blo: T 200mA @ 115VAC T 100mA @ 230VAC Input Loop Parallel Serial Ground Lift Loop Off 75 Termination ANALYZER 28
29
31 30
32 33 34 35 36 37 38 39 40 41 42 43 44 Rear Panel 28. Voltage Selector & Fuse drawer: Selects 115VAC or 230VAC & holds the main fuse and a spare. 29. Power In: IEC 320 power inlet. 30. Ground Lift Switch: Isolates chassis ground from signal ground. 31. Color ID In & Loop: Input & loop for color field ID pulse. 32. Termination: 75 for video in & loop. 33. Video Reference In & Loop: BNC jacks for video reference. 34. Video Out (optional): Report output. 35. Dipswitches: Future upgrades - pg 9 36. Serial Port: DB-9M for RS-232 I/O. 37. Parallel Port: DB-25F for Centronics printer output. 38. Relay out / in: TRS 1/4" for remote "Good Code" LED or extl trigger input. 39. Tone Out: Output of the Stripper. 40. Output 1-4 (40-43): Outputs of the Distributor/ Reshaper. 44. Input A: Rear panel time code input. Table of contents Page 1 Table of contents
· Introduction ................................................................................................. 2 · Section 1: Setting up the SR-15+ Connections ........................................................................................... 3 Wiring ................................................................................................... 4 Setting the SR-15+'s jumpers .................................................................... 6 Setting the SR-15+'s dipswitches ............................................................... 9 · Section 2: Using the SR-15+ 1. Time Code Analyzer Time Code Format and Frame Rate .................................................. 10 Frame Rate vs. Format / 29.97 vs. Drop Frame ........................ 11 Proper bit width ...................................................................... 11 Time Code / Video Phase .............................................................. 12 What does it mean for time code to be in phase with video? ...... 12 How can you check video phase? ............................................ 12 Color Framing ......................................................................... 13 Reporting Time Code Errors ............................................................ 14 What is the difference between Reset and Clear? ....................... 15 How do you reset or clear the SR-15+? ..................................... 15 Transmitting A Time Code Report ..................................................... 16 Using a printer with the SR-15+ ................................................ 16 Using a computer with the SR-15+ ............................................ 16 Time Code Report .................................................................... 17 Serial Time Code Addresses ..................................................... 18 2. Tone Stripper How to strip a pilot tone ........................................................... 19 How to read the frequency of the stripped tone .......................... 19 Stripper conversions ................................................................ 19 3. Distributor / Reshaper Time Code Distribution ............................................................. 20 Reshaping distorted time code .................................................. 20 Time Code Level ...................................................................... 20 Selecting the proper rise time .................................................... 21 Reshaping Vs. Re-generating .................................................... 21 · Section 3: Application notes ........................................................................ 22 · Appendix A: Time Code Error Messages ................................................................ 25 B: More on the Frame Rate Counter ........................................................ 26 C: Extracting 62.50Hz tone from 25 fr/sec code ..................................... 26 D: Protecting the SR-15+'s outputs from DC voltage on the load ................ 26 E: More on the video phase display ....................................................... 27 F: Identifying color field with time code address ....................................... 27 G: Longitudinal Bit Assignment (SMPTE & EBU) ........................................ 28 · Specifications .............................................................................................. 29 Page 2 Introduction Introduction
The SR-15+ time code distripalyzer combines three functions in one unit: a distributor, a stripper and an analyzer. It should be permanently installed in your time code set up and always on line, whether you are generating time code and recording it on tape or playing it back while synchronizing several machines. This way, the SR-15+ can detect time code errors immediately, before you commit any recording to bad time code. · The Distributor reshapes time code and distributes it through 5 individually buffered outputs; · The Stripper extracts a synchronous field rate pilot tone from time code, video or AC mains; · The Analyzer identifies the type, the stability and the frame rate of the incoming time code; it verifies its proper synchronization (phase) with video; and it reports time code errors (i.e. drop outs...). INPUTS
A (Rear) OUTPUTS
RESHAPER Time Code
B (Front) 1 2 3 4 5 T I M E C O D E STRIPPER Sine AC Mains Tone
Square
Front Panel Display ANALYZER Video Color Pulse Serial / Parallel
Optional Video Card
Good Code LED Printer/ Computer
Beeper Video Monitor
Relay out Event In Relay Figure1. SR-15+ Flow Chart Set Up Page 3 Section 1: Setting up the SR-15+ 1. Connections
Time Code inputs The SR-15+ has 2 separate input jacks for time code: Input A on the rear panel and Input B (aux) on the front panel. The front panel "Input Select" switch determines which input is active. Connect your main time code source to the rear panel input jack. The front input jack is provided for an auxiliary time code source. Time Code and Tone outputs There are 5 reshaped time code outputs: 1 through 4 are located on the rear panel and output 5 is on the the front panel. Connect these outputs to your synchronizer, reader, console automation, sequencer, workstation etc... The Pilot Tone output is located on the rear panel. Connect this to your tone destination (i.e tape machine, resolver...). Video Reference Connect Video Composite Sync or Composite Video to the video reference input BNC. This signal is used by the Analyzer to monitor phase with time code and by the Stripper to extract a video referenced pilot tone. An additional BNC connector is provided for looping through as well as a switchable 75 termination. Color ID If using Color Framed Time Code, connect the Color Field ID pulse from your house Sync Generator into the rear panel Color ID input. When this pulse is present, the SR-15+ reports the time code alignment with respect to this reference. There are 2 BNC connectors on the rear panel: Color ID Input and Loop. Video Out (optional) Connect a video monitor to this BNC connector to view the time code report or to burn a time code window in your video. Relay Out/In This 1/4" jack can be set up as an input or an output (see "Setting up the SR15+'s jumpers"). If used as an output, connect a remote "Good Code" LED to this jack; If used as an input, connect an external switch to this jack. Parallel Port Connect a parallel printer (Centronics) to this port to print a time code report. Serial Port (RS-232) Connect a serial printer to this port to print a time code report or a computer such as a Mac or a PC to capture the report on the screen and to access the SR-15+ to customize your report (future software upgrade) - see next chapter for proper wiring. Page 4 Power Set Up CAUTION: BEFORE CONNECTING TO AC MAINS BE VERY SURE THAT THE CORRECT VOLTAGE IS SELECTED ON THE REAR PANEL AND THAT THE PROPER FUSE IS INSTALLED. The SR-15+ can operate with 115 VAC / 230 VAC @ 50Hz / 60 Hz. To change selected voltage: disconnect the power cord; open cover of power entry module using small blade screwdriver; remove the plastic selector by pulling it out and select desired voltage; replace selector into unit and close cover making sure the selected voltage appears in connector window.
Main fuse drawer (hot side) Voltage selector
~ 115Vac Spare fuse drawer Figure 2. Rear panel power entry module (open) IMPORTANT: if you change the voltage setting, you MUST also change the fuse: In addition to the voltage selector, the power entry module also holds two fuse drawers. Since only the hot side is fused, the second drawer is not in the circuit and only serves to hold a spare fuse (see drawing above). Pull the main fuse drawer using a small blade screwdriver and check the markings on the fuse. Use the following values: @ 115VAC: 250V T200mA (slow blow, type 218) @ 230VAC: 250V T100mA (slow blow, type 218) 2. Wiring
XLR Connectors: The SR-15+ uses XLR connectors for time code and tone inputs and outputs. Pins are: 1=ground, 2=high, 3=low. Since time code is bi-phase, a reversal of low & high wires would not cause a problem. The tone however would be 180° which may cause a 1/2 frame error when jam syncing to tone. The SR-15+ works with balanced and unbalanced equipment. It can balance an unbalanced signal. This can eliminate problems due to mismatched impedance and ground loops. When using unbalanced equipment with the SR-15+, wire your cables as described in the diagrams below.
+
2 1
2 3 1 3 + SR-15+ Input SR-15+ Output Figure 3. Proper unbalanced wiring diagrams 1/4" Jack (Relay out/in) This is a tip-ring-sleeve jack. It can be an output or an input depending on the position of jumpers 4 & 5 (see "Setting the SR-15+'s jumpers"). As an output, the 1/4" jack is connected to an internal relay which is activated whenever the "Good Code" LED goes on. The pins are: Tip = normally open / Ring = common / Sleeve = normally closed. Set Up Page 5 As an input, the jack is connected to the analyzer so that the SR-15+ can report each closure (from an external switch or relay connected to this jack) along with its coinciding time code address. Closure needs to be between tip and sleeve for a minimum of 1/10 second. IMPORTANT: You must use a stereo plug (TRS type) since a mono plug would cause a short between ring and sleeve.
SR-15+ RELAY RING TIP SLEEVE TIP
RING SLEEVE n.c. Relay out
Figure 4. 1/4" Jack pins Event in Ext. trigger Parallel Port (DB-25F) Use a regular Centronics cable (DB25P - CEN36P) to connect a parallel printer to this port. Serial Port (DB-9M) Only 3 pins are used on this connector: Pin 2 is RS-232 out (TXD); pin 3 is RS-232 in (RXD); pin 5 is ground. To connect a computer, follow the instructions below: · Mac: make up a cable with an 8 pin mini Din connector on the Mac side and a 9 pin sub-D female connector on the SR-15+ side. Solder the 3 pins needed as described in the table below. Note: For convenience, you can use a standard modem cable and replace one of the Din connectors with a DB-9F. Pins 4 (SG) and 8 (RXD+) are usually tied on the Mac side which is OK.
SR-15+ 9 pin Sub-D Signal Out Signal In Ground 2 (TxD) 3 (RxD) 5 (SG)
6 3 7 8 4 5 1 2 8 pin Mini Din Mac 8 pin Mini Din 5 (RxD) 3 (TxD)) 4 (SG) · PC: make up a cable with 25 pin sub-D on the the PC side and a 9 pin sub-D female connector on the SR-15+ side. Solder the 3 pins needed as described in the table below. IMPORTANT: ON THE PC SIDE (25 PIN SUB-D), PINS 6 AND 20 (DSR - DTR) MUST BE TIED TOGETHER.
SR-15+ 9 pin Sub-D Signal Out Signal In Ground 2 (TxD) 3 (RxD) 5 (SG) PC 25 pin sub-D 3 (RxD) 2 (TxD) 7 (SG) 6 (DSR) 20 (DTR) · Serial printer: To connect an Apple ImageWriter printer, use the above described Mac cable. For serial printer with a DB25 connector, use the PC cable. For other printers, refer to your printer's manual for pin configuration. Page 6 Set Up 3. Setting the SR-15+'s Jumpers
There are 5 jumpers on the SR-15+'s mother board that control the 4 different functions listed below. To change the factory settings, remove the chassis' top panel and move the jumpers as follows:
JP3 Latching - Momentary JP4 JP5 Out - In In - Out JP7 Switched - Rear JP6 Code - Tone Figure 5. SR-15+ Top view INPUTS
RESHAPER OUTPUTS 1 2 3 4 5
T I M E C O D E Time Code
B (Front) 123 A (Rear) JP7 STRIPPER Sine JP6
321 AC Mains Tone
Square ANALYZER Video Color Pulse Serial / Parallel
Optional Video Card
Good Code LED Printer/ Computer
Beeper
t s r Video Monitor
Relay out/ Event in JP3 Relay 123 123 JP5 JP4 Figure 6. SR-15+ Flow Chart with Jumpers Set Up Reshaper's input: "Switched" / "Rear" (JP7) Page 7 The front panel input selector switch determines which input is active, front or rear. This input signal is reshaped and distributed as well as analyzed by the SR-15+. However, in some situations, it may be convenient to reshape and distribute one signal and analyze another. Jumper JP7 enables you to do that by changing the reshaper's input path. JP7 has 2 settings: "Switched" and "Rear". In the "Switched" setting, the input selector switch controls the input to the analyzer and the reshaper; in the "Rear" setting, the rear time code input is directly connected to the reshaper, bypassing the input selector switch (front panel). In this mode, the selector switch controls the analyzer's input only.
Rear Input
Input Selector Switch RESHAPER Rear Input
Input Selector Switch RESHAPER Front Input ANALYZER Front Input ANALYZER Figure 7. "Switched" position Figure 8. "Rear" Position With JP7 set to "Rear", you can analyze an auxiliary time code patched into the front panel input jack without disrupting the reshaping of the master time code patched into the rear panel input jack. This feature also enables you to analyze the reshaped signal if needed. Sometimes, time code is so distorted that the SR-15+ cannot analyze it properly. If this is the case, set JP7 to "Rear" and patch the front panel output into the front panel input (use a short XLR cable). With the input selector in the "Front" position, the SR-15+ analyzes the reshaped time code; with the input selector in the "Rear" position, the SR-15+ analyzes the "raw" time code.
Time Code Source
Rear Input
Input Selector Switch RESHAPER
ANALYZER Output 5 (front) Front Input XLR Cable
Figure 9. With JP7 in "Rear" position, you can analyze the reshaped time code. The SR-15+ is shipped with the jumper in the "Switched" position. NOTE: When extracting a pilot tone from code, the Stripper section always follows the front panel input selector switch, regardless of JP7's position. Tone output: Tone / Code (JP6) The Tone output can be converted into a sixth Time Code output if needed. To do so, move the shorting jumper on JP6 to the left position ("Code"). In this mode, the Stripper section of the SR-15+ no longer has an output. The Tone pot on the front panel (Stripper section) controls the level of the 6th code output ("Tone Out" XLR). The SR-15+ is shipped with JP6 in the "Tone" position. Page 8 Set Up 1/4" Jack: Relay out / Event In (JP4 & JP5) The rear panel 1/4" jack can serve as an input or as an output: · Output setting: the 1/4" jack is connected to an internal relay which is activated whenever the "Good Code" LED goes on; · Input setting: an external switch can be connected to the 1/4" jack so that the SR-15+ can report each closure along with its coinciding time code address. For "Relay out": move shorting jumper on JP4 to the left and on JP5 to the right. For "Event in": move shorting jumper on JP4 to the right and on JP5 to the left. The SR-15+ is shipped with the 1/4" jack set for "Relay out". Relay: Latching / momentary (JP3) The internal relay has 2 different modes of operation: · Latching: the relay is open when the "Good Code" led is off and closes when the led is on. · Momentary: the relay closes for approximately 100ms when the "Good Code" led goes from on to off; The SR-15+ is shipped with the relay in the "Latching" mode. To set it to the "Momentary" mode, move the shorting jumper on JP3 to the 2 pins closest to the front panel. Set Up Page 9 4. Setting the SR-15+'s Dipswitches (rear panel)
Fuse, Slo-blo: T 200mA @ 115VAC T 100mA @ 230VAC There are 8 switches on the SR-15+'s rear REFERENCE COLOR ID VIDEO panel. Most of these switches are reserved for Iso Grnd Loop Input Input future upgrades.
Isolated Grounded VID OUT
(Optional)
R RELAY OUT/IN
T S TONE OUT 115 Vac Parallel
1 2 3 4 5 6 7 8 Serial Lift Only two switches are presently used. Ground Loop Off 75 Termination ANALYZER Switch #1: Not used - Future upgrade Switch #2: Not used - Future upgrade Switch #3: Not used - Future upgrade Switch #4: Not used - Future upgrade Switch #5: Not used - Future upgrade Switch #6: Not used - Future upgrade Switch #7: This switch is used for selecting 4 or 8 fields PAL color sequence. The default setting (off or up position) is for 4 fields; the other (on or down position) is for 8 fields. See page 13 for more on color framing. Switch #8: With this switch off (up position), the time code report is transmitted through both the serial and parallel ports (see page 17). Turning switch #8 on (down position) disconnects the parallel port and changes the serial port output so that, instead of transmitting the regular time code report, the serial port transmits time code addresses as ASCII characters (see page 18). Page 10 Analyzer Section 2: Using the SR-15+ 1. Time Code Analyzer
The Analyzer section has 3 main functions: · to identify the format and frame rate of the incoming time code; · to verify the proper synchronization (phase) with video; · to detect and report time code errors. A. TIME CODE FORMAT & FRAME RATE When playing time code into the SR-15+, the analyzer first identifies its format: Reader Display: As soon as valid time code is recognized, its format (or frame count) is indicated in the 8 digit display for about 2 seconds. The display then automatically switches to its selected mode (time code, user bits or video ø). THE 3 STANDARD TIME CODE FORMATS ARE: 24, 25 OR 30 FR/SEC. The 4 LED's on the right of the display further identify the time code: · The ASCII LED indicates the user bits' format. If the LED is off, UB format is Hex; if the LED is on, UB format is ASCII. ASCII is often used to identify a scene, reel, date or camera number . · The Color Frame LED indicates whether code is "color framed" or not. This LED comes on if the color flag is set (bit 11); it is off if the flag is not set. For more on "Color Framing", see page 13. · The Drop Frame LED indicates the drop-frame status. This LED comes on as soon as the microprocessor detects a drop frame flag (bit 10 set). But the SR-15+ also monitors the code to make sure the proper frames are actually being dropped. If they are not, the LED blinks mostly off (false flag). If frames are properly dropped but the DF flag was not detected, the LED blinks mostly on (missing flag). Note: Since frames are dropped at the end of the minutes, this LED will not start blinking until the microprocessor sees a minute boundary of good code. · The Video Code LED : Indicates whether code is in sync with video or not. This LED comes on only if a video reference is present. For the different modes of this LED, see page 12. The 4 digit display indicates the frame rate (or frequency). The SR-15+ strips the bit clock from the incoming time code and displays it as frames per seconds. It displays any rate from approximately 21 to 39 fr/sec. The frame rate counter is updated 4 times per second. Since its resolution is ± .01 fr/sec, it can show potential problems such as jitter (see Appendix B "More on the frame rate counter"on page 26 ). Fr/Sec
Hz Analyzer Page 11 Format vs. Frame Rate The SR-15+'s 4 digit display indicates frame rate, NOT format. There is a distinction. The format does not deal with frequency. It is a way of counting: at 30 fr/sec, the frame sequence is: 28, 29, 00, 01, etc... at 25 fr/sec, the frame sequence is: 23, 24, 00, 01, etc... at 24 fr/sec, the frame sequence is: 22, 23, 00, 01, etc... The frame rate on the other hand does not deal with count but frequency. If the tape speed varies, the frame rate varies. For example, if a tape machine was running 5% too fast, a format of 24 fr/sec would have a frame rate of 25.20 fr/sec. Yet the format would remain 24 fr/sec. 29.97 vs. Drop Frame Many people confuse 29.97 with drop-frame but they are not the same thing: 29.97 indicates a rate (frequency) and drop-frame indicates a format (count). "29.97" time code is 30 fr/sec code with a rate of 29.97. When generating 29.97 time code, the generator locks to a field rate of 59.94 Hz (NTSC color rate) and pulls down the frame rate by .1% to 29.97. But the format or frame count remains 30 fr/sec. Drop Frame on the other hand is another way of counting frames. It is a variation of 30 fr/sec format, invented to compensate for the color rate of 29.97. Drop frame code leaves certain frame numbers out so that one hour of code time equals one hour of stopwatch time when code is running at 29.97. Drop and non-drop code can both be generated at a rate of 30 or 29.97 fr/ sec. For that reason, the frame rate and the drop frame status are displayed separately on the SR-15+'s front panel. Proper bit width In LTC, each word is divided into 80 equal segments called bits, numbered 0 to 79 (for bit assignment, see appendix G on page 28). Each bit can either be a "one" or a "zero": a "one" has a level shift halfway though its width; a "zero" does not. The time between each level shift can easily be calculated: At 30 fr/sec it is 417µs for a "zero"and 208µs for a "one", At 25 fr/sec it is 500µs for a "zero"and 250µs for a "one", At 24 fr/sec it is 521µs for a "zero"and 260µs for a "one".
417µs 417µs
208µs "Zero" "One" Figure 10. Bit width at 30 fr/sec. The SR-15+ has a ±25% window which means that at 30 fr/sec, the level of a "zero" could remain constant for 313 to 521µs and of a "one" for 156 to 260µs. However, some VCR's distort the bit width beyond that window (the "one's" become too narrow). If the SR-15+ does not recognize valid time code with a signal present at its input for over 1 second, it switches automatically to an alternate setting to accommodate these distortions. If time code is then recognized, a "alternate bit width window" message is reported in the time code report. The SR-15+ remains on this alternate setting until reset (automatically or manually). Page 12 B. TIME CODE / VIDEO PHASE What does it mean for time code to be in phase with video? Analyzer When time code is recorded on video tape, it must be synchronous with the video signal, meaning that the beginning of each time code word must coincide with the beginning of the video frame it describes. This is essential for video editing. There is one time code word for each frame. Each word is made up of 80 bits, numbered from 00 to 79 (see diagram below). Time code is phased properly with video when the end of bit 79 of time code lines up with field 1 line 5 of video (± 1 line).
ONE TIME CODE FRAME (12:35:08:28)
Sync Word
64 68 72 76 0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 Sync Word
68 72 76 0 4 F1L5 Video Field 1 F2L5 Video Field 2 F1L5 ONE VIDEO FRAME
Figure 11. Proper alignment of time code and video How can you check video phase with the SR-15+? The Video Code LED indicates 4 different conditions: on means: time code is properly phased with video; blinking mostly on means: time code is resolved with video but out of phase; blinking mostly off means: time code is non-synchronous (drifting); off means: no video is present. The SR-15+ considers time code "properly phased" if the time code bit lined up with video F1L5 is between numbers 75 and 04. The SR-15+ considers it "non-synchronous" if time code moves by more than 2 bits with respect to video F1L5. If the time code generator was mistakenly set to internal crystal instead of external video, there would be a very slow drift between time code and video. The SR-15+ reports this drift as soon as time code moves by more than 2 bits with respect to F1L5, even if it is within the "properly phased" window. On the reader display you can monitor the sync between time code and video: With its selector switch in the "video ø" position, the reader shows which bit of the time code word lines up with video Field 1 Line 5 ("V" drive). With synchronous code, the display should read: "bit 79". In the real world however, things are different and phase will often be slightly off. For example, if the display reads "bit 68" or "bit 07", the address track was possibly misaligned on the VCR and your synchronizer may show some slight sub-frame offset (i.e. 03,12, etc) when locked to code like this. So long as you are within a few bits of 79 and the bit number stays the same, you should have no problems. Note: If "V" drive is at the edge of a time code bit, 2 bit numbers (those on either sides of that edge) will flicker in the display. WARNING: IF THE BIT NUMBER DRIFTS, TIME CODE IS ASYNCHRONOUS AND MAY BE USELESS FOR YOUR APPLICATION. Analyzer Color Framing Page 13 The signals carrying color information within the video signal (chrominance) follow their own cyclic evolution. The relationship between the color subcarrier and the video sync is too complex to describe here, but it is important to know that this relationship must be maintained during editing to avoid picture disturbance. For NTSC, SECAM and simple PAL editing, the color sequence is spread over 4 fields (2 frames); for more complex PAL editing, it is spread over 8 fields (4 frames).
COLOR PULSE VIDEO TIME CODE FIELD 1 FIELD 2 FIELD 3 FIELD 4 FIELD 1 72 76 0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 0 4 8 12 16 20 24 28 32 FRAME A FRAME B FRAME A Figure 12. NTSC 4 Field Color Sequence A "color frame" standard was developed for SMPTE and EBU time codes so that the position of each frame in the color sequence could be identified by using the time code address rather than the video signal (see Appendix F on page 27). When generating such time code, the field ID pulse from the house sync generator is fed into the time code generator. The time code generator locks to that pulse (so that the first time code frame of the color sequence begins at the ID pulse) and sets a flag (bit 11) to identify color framed time code. How can you check proper color framing with the SR-15+? To verify the proper color framing of your time code, connect the field ID pulse from your house sync generator into the SR-15+'s Color ID input (rear panel BNC). NOTE: With EBU, you must let the SR-15+ know if the color sequence is 4 or 8 fields long. Turn dipswitch #7 on for 8 fields and off for 4 fields (see page 9) Reader Display: When the selector switch is set to "video ø", the first digit of the display shows which field, derived from the time code address, is aligned with the ID pulse. If no pulse is present, the SR-15+ puts a dash across the first digit. IMPORTANT NOTE: The SR-15+ does not extract the field numbers from the video signal but from the time code address. Color Frame LED: If the color flag is set (i.e. time code bit 11 is a binary one), this led comes on; if not, it stays off. Page 14 C. REPORTING TIME CODE ERRORS Analyzer One of the functions of the analyzer section is to detect and report time code errors. Errors considered serious enough to cause a synchronizer problem (such as a repeated frame) are labeled "fatal" by the SR-15+. Others are "non-fatal". For a complete list, see appendix A on page 25. Reporting errors on the SR-15+ front panel All "fatal" errors are reported on the front panel; "fatal" and "non fatal" errors are both reported on the printed report. The 8 digit display: Every time the SR-15+ detects a "fatal" error, the reader is momentarily interrupted and displays a description of the error (i.e. "Drop-out" etc...) for about 2 seconds. Then it returns to its selected mode of operations (time code, user bits or video ø). After the SR-15+ has detected a "fatal" error, the first digit of the reader display blinks continuously (until cleared or reset). This way, if you leave the room, you will know if an error occurred while you were away. After tape has been stopped (code must be interrupted for at least 5 seconds), the 8 digit display shows a description of the first "fatal" error detected for about 2 seconds. After these 2 seconds, it indicates where the error occurred and then alternates between the faulty address and its description. If no error occurred, the display alternates between a "Code Stopped" message and the last valid time code address. View the first five errors: The SR-15+ keeps the first 5 errors detected in memory. After time code has been stopped, tap the reset button to toggle through them. Each tap advances the display to the next error until the fifth one. Then it returns to the first. For each error, the display alternates between the faulty address and its description. Front panel error messages: Here is a list of error messages as they are reported on the 8 digit display: DROP OUT: Drop out - Code interruption for less than 1 second. CODESTOP: Code Stopped - Code interruption for 1 second or more. DISCONT: Discontinuous Address or repeated frame INVALID: Invalid Address - Any non valid number such as 39 frames. VID-LOST: Video Loss - Any interruption in the video signal. FORM CHG: Format Change DROP X: Wrong number of frames dropped (X indicates the number of frames) DROP CHG: Change in the Drop Frame Status COLR CHG: Change in the Color Frame status Analyzer Page 15 In addition to the 8 digit display, the SR-15+ also alerts you of errors as follows: The "Good Code" LED (input section) blinks off momentarily whenever a "fatal" error is detected. The Beeper sounds whenever the "GOOD CODE" LED changes from on to off. If necessary, the beeper can be turned off via the front panel on/off switch. The Event Relay is activated whenever the front panel's "GOOD CODE" LED goes on. This relay has 2 different modes of operation (see"Setting the SR-15+'s jumpers" on page 8): · Latching: the relay is open when the "Good Code" led is off and closed when led is on. This can be used to connect a remote "good code" LED. · Momentary: the relay closes approximately 100ms when the "Good Code" led goes from on to off. This can be used to stop the tape machine as soon as a fatal error is detected, for example. The SR-15+ keeps track of errors and statuses on the front panel and it may be useful at times to reset the SR-15+ or clear some of its displays. What is the difference between Reset and Clear? · Reset: When you reset the SR-15+, it is as if you were playing new time code. After a reset, the SR-15+ begins the normal sequence again: - the SR-15+ identifies the time code format and displays it for about 2 seconds in the 8 digit display (see page 10); - the front panel LED's are all reset; - the "first 5 errors" register is erased; - a new time code report is initiated (through the serial & parallel ports). · Clear: A "Clear" command clears some of the SR-15+'s displays: - If an error has been detected and the 1st digit of the reader is blinking, a clear command stops the blinking and clears the "first 5 errors" register (i.e. the next error detected will now be considered to be the first error). - If the video code LED was blinking, a clear command stops the blink and resets the LED. How do you reset or clear the SR-15+? · Manual Reset: To manually reset the SR-15+, press and hold the reset button for at least 1 second. The 8 digit display will say: "- reset -" · Auto Reset: When code is interrupted for at least 5 seconds an end of report is initiated. When code is reintroduced, the SR-15+ is automatically reset. · Manual Clear: Tapping the reset button while code is running clears the displays as described above. · Auto Clear (partial): When code is interrupted for at least 1 second, the video code LED is automatically cleared when code is reintroduced. Page 16 D. TRANSMITTING A TIME CODE REPORT Analyzer A complete report including "fatal" and "non-fatal" errors as well as format information can be sent to an external printer or computer through the rear panel parallel and serial ports. Using a Printer with the SR-15+ To send a time code report to a printer, connect it to the appropriate port, turn it on and set it so that it is ready to print ("on line"). When you play time code into the SR-15+, a report is immediately initiated (see time code report on page 17). The header is first printed, as well as the format, the video reference information and the start time. The SR-15+ then prints the title "address errors" and waits for errors to happen. As soon as they occur, the faulty address and a description of the error is printed. An end of report is printed automatically when time code is interrupted for at least 5 seconds. This includes a summary and the end time. In the summary, the SR-15+ reports general comments such as Time Code properly synced with Video (or not) and non standard formats such as Color Framed Code not synced with Video or 25 Drop code etc... Both serial and parallel printers can be used with the SR-15+. However, you should use the kind of printer that prints one line at a time such as dot matrix printers and not full page printers such as laser printers. If you want to use a laser printer, you should first send the report to a computer, as described below, then send the report from the computer to the laser printer. This would also allow you to customize the report, if needed, by adding information such as the date, the name of the studio, the name the client, etc... Using a Computer with the SR-15+ 1. Connect the SR-15+ to a serial port of your computer (see page 5 for wiring information). On the Mac, you can use the Modem or the Printer port. 2. Launch any communication program (i.e. modem program), set your computer for direct connection (not through phone connection), select the proper serial port and set the speed and format as follows: Transmission speed: Bits per character: Stop bits: Parity: 9600 baud 8 1 None 3. The procedure to send a report to a computer is identical to the one for a printer: as soon as you play time code into the SR-15+, a report appears on the screen. If any errors are detected, they will be reported as they occur. An end of report will automatically be generated as soon as input is interrupted for at least 5 seconds. Analyzer Time Code Report The time code report includes 7 sections: 1. Header Line 1: BRAINSTORM SR15+ VER #.## Line 2: TIME CODE DISTRIPALYZER Line 3: TIME CODE REPORT 2. Format: Frame count & drop status : 24, 25, 30 Drop Frame or 30Non Drop Color bit status: reported only if active : Color Bit active Parity bit status: reported only if active: Parity bit active User Bits format: User Bits: HEX or ASCII User Bits message: first UB message detected is printed Page 17 BRAINSTORM SR-15+ Ver 3.05 Time Code Distripalyzer TIME CODE REPORT Alternate Bit Width Window *** FORMAT *** 30 Drop Frame Color Bit active User bits: HEX 01234567 *** VIDEO REFERENCE *** Present "V" drive at bit 79 *** START TIME *** 01.00.00.00 *** ADDRESS ERRORS *** 01.12.36.05 01.18.41.23 01.18.41.27 01.23.45.07 Drop out Bad bits: 28 Frame repeated Code stopped *** SUMMARY *** VIDEO SYNC: Code Properly Synced COLOR: Field 1 locked with color ID pulse *** END TIME *** 01.23.45.07 END OF REPORT NOTE: If SR-15+ had to switch to the alternate setting to read time code (see "Proper bit width" on page 11), the following message is printed just above the "Format" heading: Alternate bit width window 3. Video Reference If video is present, the SR-15+ reports which bit of time code is lined up with "V" drive (video field 1 line 5) 3 seconds after time code is detected (to allow for ramp up time); if video is not present, the SR-15+ reports: Video not present. 4. Start Time First valid Time Code address. 5. Address Errors The SR-15+ prints the title "ADDRESS ERRORS", then waits for errors to occur. As soon as an error is detected, the faulty address and the error description are transmitted. 6. Summary When input is interrupted for 5 seconds, an end of report is printed which includes the following:: Video Sync (if video reference was present): code properly synced / resolved but out of phase / non synchronous Color Framing (if color flag was set and color pulse was present): Field X locked with color ID Non-standard formats (if applicable): 24DF / 25 DF / non synchronous color code / Undefined bit set 7. End Time The last valid address is printed at the very end of the report. Page 18 Serial Time Code Addresses Analyzer In some situations, when analyzing time code, it is useful to view each address sequentially to make sure that no frame is missing or repeated etc... Pressing switch #8 on (down position) changes the serial port output so that, instead of transmitting the regular time code report, the SR-15+ uses the serial port to transmit time code addresses to a computer screen. These numbers are transmitted as ASCII characters. The computer screen displays each time code address, as read by the SR15+, one per line. Whenever time code is interrupted for 1 second or more (i.e. code stopped), a line is skipped. Whenever a fatal error is detected, the corresponding time code address is moved one space to the right so that it can easily be found when scrolling through these addresses. 00:01:20:08 00:01:20:09 00:01:20:10 00:01:20:11 00:01:20:12 00:01:20:13 00:01:20:14 00:01:20:15 00:01:20:15 00:01:20:16 00:01:20:17 00:01:20:18 00:01:20:20 00:01:20:21 00:01:20:22 Code Stopped Fatal Error (repeated frame) Fatal Error (missing frame) This serial output should be sent to a computer with scrolling capabilities since at 30 frames per second, just a few seconds will fill several screens and it would be necessary to scroll up and down to find the trouble spot. Stripper Page 19 2. Tone Stripper
The SR-15+ can extract a pilot tone (at field rate) from time code, video or AC mains. This tone is synchronous with its source. Its zero crossing is synchronous with and its waveform rises at: · the end of the sync word (bit 79) of the code source, · F1L5 of external video source or · the 0 crossing of AC mains source Sync Word Sync Word
0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 0 4 Time Code
64 68 72 76 Pilot Tone Video
F1L5 VIDEO FIELD 1 F2L5 VIDEO FIELD 2 F1L5 Figure 13. Alignment of pilot tone in reference to code and video To strip a pilot tone: 1. select the source (time code, video or AC mains), 2. select the waveform (sine or square), 3. set the output level. To read the frequency of the stripped tone:
Fr/Sec Hz The 4 digit display is a hi-resolution frequency counter. To read the frequency of the stripped tone, set the 4 digit display selector to "Tone Out". To read the frequency of a recorded tone: You can also read the frequency of an external tone: patch it into the selected XLR input and set the 4 digit display to "Tone In". The SR-15+ reads any frequency from 5 to 99.99 Hz. If a tone is patched into the SR-15+, the 8 digit display reads: " - tone - ". The Stripper does the following conversions: Code 29.97 fr/sec ................ 30 fr/sec ..................... 25 fr/sec ..................... 24 fr/sec ..................... NTSC Color ................. PAL .............................. 59.94 Hz 60 Hz 50 Hz 60 Hz 59.94 Hz 50 Hz Video Page 20 Distributor / Reshaper 3. Distributor / Reshaper
TIME CODE DISTRIBUTION In today's studio, more and more pieces of equipment rely on time code for precise timing: console automations, sequencers, DAW's, readers, synchronizers, editors etc... Simply multing a single output of a tape machine or of a generator is not recommended because it can cause serious problems: · Multing a single output ties the destinations' inputs together. If one piece of gear is misswired and creates a short, all destinations will be affected. This could easily happen since, until recently, there was no universal standard regarding XLR pins 2 and 3. · Heavy loading from high capacitance cables and/or low impedance loads can cause source distortions and instability. The SR-15+ eliminates these problems by providing 5 individually buffered and balanced outputs. In addition to distributing time code, the SR-15+ also reshapes it. RESHAPING DISTORTED TIME CODE When time code comes off a tape machine (especially VCR's), it usually has improper rise/fall times, leading edge peaking and different amplitude levels on "one's" and "zero's" (see diagrams below). This is due to the fact that analog tape machines were not designed to record a signal that is basically digital. Figure 14. Analog tape machine Play speed Figure 15. Analog tape machine High speed Figure 16. Analog tape machine Low speed This can make the time code difficult or sometimes impossible to read. The SR-15+ eliminates these amplitude distortions by reshaping the code to its original SMPTE or EBU specifications. TIME CODE LEVEL Some readers operate best when time code is at a specific level. The problem is that this is not necessarily the level at which it was recorded. Also, if this level fluctuates and/or drops below the reader's threshold, time code can become unreadable. With the SR-15+, you can adjust each output level individually so that optimum levels can be sent to each reader. These levels will remain constant regardless of input level fluctuations. Since the SR-15+'s input threshold is lower than many readers (better than -30dB), it can reshape and recover time code that many synchronizers can't read. Distributor / Reshaper SELECTING THE PROPER RISE TIME Page 21 Per SMPTE and EBU specifications, the rise time limiting is used to minimize crosstalk from time code into audio. A longer rise time removes more high frequency components from its waveform. However some equipment may not be able to read time code if its rise time is too long. The SR-15+ has three preset rise times for its output waveform: 25 µsec (SMPTE), 1µsec (square wave) and 50µsec (EBU). Figure 17. Reshaped Code SMPTE setting (25µs.) Figure 18. Reshaped Code Square setting (1µs.) Figure 19. Reshaped Code EBU setting (50µs.) As a general rule, if time code is patched directly into a reader, use the square wave position; but, whenever possible cross-talk problems exist (i.e. in an audio patchbay...) or when recording the reshaped signal, use the SMPTE or EBU setting (as needed). RE-SHAPING VS. RE-GENERATING When doing transfers, some engineers like to pre-stripe time code onto tape, others like to reshape time code and others prefer to regenerate it. In most situations, pre-striping the tape while the tape machine is running at its own internal fixed speed is the best solution. Assuming that the generator is working properly, this would insure a clean and error free time code track. The audio tracks could then be transferred while the master and slave machines are locked. If you choose instead to reshape or regenerate, it is important to recognize that they are different and what their drawbacks are. A reshaper does not generate new time code. It cleans up an existing time code by eliminating amplitude distortions. This means that the reshaped time code is always identical to the source time code. However, if the source is temporarily interrupted (i.e. drop out), a reshaper does not fill the gap. Also, timing distortions (i.e. jitter, wow or flutter) are transferred through a reshaper. Regenerating time code on the other hand requires a generator. When regenerating, the generator reads an external time code source and regenerates a new code which has the same frame numbers. Regenerating can be used to repair drop outs, eliminate timing distortions or insert user bits. However, when regenerating, it is extremely important to set the generator properly. Some generators can be set to accept two reference sources, one supplying the frame numbers and another supplying the clock (frame rate). If those two sources are not synchronous, errors will be generated. For example, if the generator is set to regenerate time code locked to video (29.97 fr/sec) and the source code has a rate of 30 fr/sec, the generator will drop some frames to make up for the slower frame rate. When transferring code by reshaping or regenerating it, you should analyze the transferred code with the SR-15+ to insure its integrity. Page 22 Application Notes Section 3: Application notes
As a general rule, it is always better to know about time code problems early rather than late in a project. More options are available early on to fix the problem and if it cannot be fixed and you have to start over, at least less time has been wasted. For this reason, the SR-15+ has been designed to be an integral part of your time code set up and, as much as possible, should always be used, not just when a problem occurs. Here are some specific suggestions regarding the use of the SR-15+: 1. When striping a tape, run time code through the SR-15+ Don't take your time code generator for granted. Maybe you didn't set it properly, maybe one of the LED's is blown, maybe the instructions are not clear, maybe it is broken. There are plenty of good reasons why your generator