A video about TBC (it is a re-edit). More samples here.
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Thank you, @Alwyn! I appreciate it!
Definitions from Tektronix (I will post definitions from other sources as well):
- Asynchronous – a) A transmission procedure that is not synchronized by a clock. b) Any circuit or system that is not synchronized by a common clock signal. c) Lacking synchronization. In video, a signal is asynchronous when its timing differs from that of the system reference signal. A foreign video signal is asynchronous before a local frame synchronizer treats it.
- Asynchronous Signals – Data communication transmission of signals with no timing relationship between the signals. Stop and start bits may be used to avoid the need for timing clocks.
- Horizontal Sync – The -40 IRE (NTSC) or the –300 mV (PAL) pulse occurring at the beginning of each line. This pulse signals the picture monitor to go back to the left side of the screen and trace another horizontal line of picture information. The portion of the video signal that occurs between the end of one line of signal and the beginning of the next. A negative going pulse from the blanking signal used to genlock (synchronize) equipment. It begins at the end of front porch and ends at the beginning of back porch.
- Vertical Sync – The pulse that initiates the vertical retrace of the electron gun from the bottom of a frame back to the top.
- Vertical Sync Pulse – a) The synchronizing pulse at the end of each field which signals the start of vertical retrace. b) The part of the vertical blanking interval comprising the blanking level and six pulses (92% duty cycle at -40 IRE units) at double the repetition rate of the horizontal sync pulse. The vertical sync pulse synchronizes the vertical scan of television receiver to the composite video signal, and starts each frame at same vertical position (sequential fields are offset by half a line to obtain an interlaced scan.)
- Black Burst – a) Black burst is a composite video signal consisting of all horizontal and vertical synchronization information, burst and in North America NTSC, setup. Also called “color black”, “house sync” or “house black”. Typically used as the house reference synchronization signal in television facilities. b) A composite color video signal. The signal has composite sync, reference burst and a black video signal, which is usually at a level of 7.5 IRE (50 mV) above the blanking level.
- Sync – a) Abbreviation for synchronization. Usually refers to the synchronization pulses necessary to coordinate the operation of several interconnected video components. When the components are properly synchronized, they are said to be “in sync”. b) Signals which control the sweep of the electron beam across the face of the display. The horizontal sync, or HSYNC for short, tells the display where to put the picture in the left-toright dimension, while the vertical sync (VSYNC) tells the display where to put the picture from top-to-bottom. c) The portion of an encoded video signal which occurs during blanking and is used to synchronize the operation of cameras, monitors, and other equipment. Horizontal sync occurs within the blanking period in each horizontal scanning line, and vertical sync occurs within the vertical blanking period.
- Composite – A television system in which chrominance and luminance are combined into a single signal, as they are in NTSC; any single signal comprised of several components.
- Composite Analog – An encoded video signal, such as NTSC or PAL video, that includes horizontal and vertical synchronizing information.
- Composite Sync – a) Horizontal and vertical sync pulses combined. Often referred to simply as “sync”. Sync is used by source and monitoring equipment. b) A signal consisting of horizontal sync pulses, vertical sync pulses and equalizing pulses only, with a no-signal reference level.
- Composite Video – a) A single video signal containing all of the necessary information to reproduce a color picture. Created by adding quadrature amplitude modulated R-Y and B-Y to the luminance signal. A video signal that contains horizontal, vertical and color synchronizing information. b) A complete video including all synchronizing pulses, may have all values of chroma, hue and luminance, may also be many sources layered.
- Locked – a) A video system is considered to be locked when the receiver is producing horizontal syncs that are in time with the transmitter. b) When a PLL is accurately producing timing that is precisely lined up with the timing of the incoming video source, the PLL is said to be “locked”. When a PLL is locked, the PLL is stable and there is minimum jitter in the generated sample clock.
- Roll – A lack of vertical synchronization which causes the picture as observed on the picture monitor to move upward or downward.
- Frame Pulse – A pulse superimposed on the control track signal. Frame pulses are used to identify video track locations containing vertical sync pulses.
- Time Base – The notion of a clock; it is equivalent to a counter that is periodically incremented.
- Time Base Error – A variation in the synchronizing signals. When time base errors are large enough, they may cause skewing or flagging distortion of the video picture.
- Time Base Corrector (TBC) – a) Device used to correct for time base errors and stabilize the timing of the video output from a tape machine. Machines like VHS players where a single pass of the video head represents many video lines are particularly susceptible to tape stretch, jitter, and speed variations which cause some recorded video lines to be shorter or longer than others. The TBC acts as a “rubber-band” storage device to line up each horizontal line at its proper location allowing for synchronous playback. b) A device used to rectify any problems with a video signal’s sync pulses by generating a new clean time base and synchronizing any other incoming video to this reference.
- Frame Store – a) Term used for a digital full-frame temporary storage device with memory for only one frame of video. b) An electronic device that digitizes a TV frame (or TV field) of a video signal and stores it in memory. Multiplexers, fast scan transmitters, quad compressors and even some of the latest color cameras have built-in frame stores.
- Frame Synchronizer – A digital buffer, that by storage, comparison of sync information to a reference, and timed release of video signals, can continuously adjust the signal for any timing errors. A digital electronic device which synchronizes two or more video signals. The frame synchronizer uses one of its inputs as a reference and genlocks the other video signals to the reference’s sync and color burst signals. By delaying the other signals so that each line and field starts at the same time, two or more video images can be blended, wiped and otherwise processed together. A TBC (Time Base Corrector) takes this a step further by synchronizing both signals to a stable reference, eliminating time base errors from both sources.
- Frame Store Synchronizer – A full-frame synchronizer used by a time base corrector with full-frame memory and can be used to synchronize two video sources.
- Asynchronous – a) A transmission procedure that is not synchronized by a clock. b) Any circuit or system that is not synchronized by a common clock signal. c) Lacking synchronization. In video, a signal is asynchronous when its timing differs from that of the system reference signal. A foreign video signal is asynchronous before a local frame synchronizer treats it.
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How about IDGAS ?
Dear Bwaak (noone else to answer pls). Why do you link to YT vids of a Eastern European (Hungarian) former member who only posted about HD Digital Video when you appear to be an American with a mission to educate about analog(e) even if 20 years too late ? -
If you have found a factual error, why would not you report it? Or, you can make your own video.
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Originally Posted by Bwaak
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"YT is full of errors. All YT videos are full of errors." This is faulty logic. Is the particular video full of errors? You would not know because you haven't even watched it. Why have you replied at all if this is not something you wanted to discuss? This is not a question, BTW, because I am not looking for an answer.
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TBC is a very controversial topic, The terms are proprietary, and the uses differ from one field to another, Broadcast, industrial and consumer to name few. There is no size fits all. The right term is not errors, but rather generalizing.
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Originally Posted by Bwaak
I didn't say your TBC video is full of errors; as you say, I didn't watch it. -
The problem here is Dunning-Kruger effect.
You're a student that suddenly wants to be the teacher. You're able to fool those who know less than you do, but not those that know more.
Your attempts to understand TBC has been rocky. Early on, months ago, you were very self-assured of your wrong understandings and facts, arrogant even, and we told you as much in this forum and elsewhere. But you've since kept reading, and are now getting less wrong.
But you're in no position to teach.
For one thing, how many TBCs have you actually used? I'd guess few to none. So you really have no basis to understand these devices. How many TBCs do you think I've used in the past 30 years? Far more than "few to none".
I've been supportive of your self-education in recent times, but your attempts to teach others is still very hamfisted.
The main problem is you keep attempting to force all TBCs into a single box, but that simply cannot be done. You must understand that TBC is a wide term, there is no single definition. That is why some TBCs are the wrong tool for certain sources or scenarios. It's why seeing the term "TBC" slapped on the box or label doesn't mean a damned thing, and never did.
I've not had time to watch the Youtube video you made, but I can say for certain that your attempted glossary in this thread is just technobabbly words, and from a company that's not even recognized as an authority on TBCs (especially not for use with consumer SD analog videotape sources).
I'm not attempting to "be mean" in this post, but I do want to be candid here. The internet has too much misinformation, often due to the person not actually understand the things for which they speak. Don't add to it.Want my help? Ask here! (not via PM!)
FAQs: Best Blank Discs • Best TBCs • Best VCRs for capture • Restore VHS -
Nice video. I'm not sure exactly what else they are wanting from you. You do go over in the video that some TBCs correct horizontal sync (line TBC - often what is built into higher end VCRs) and some correct vertical sync (vertical jitter and usually will blank the top several lines which contain macrovision - blanking the macrovision area out is also termed vertical blanking interval setting on some TBCs), most single devices don't do both horizontal and vertical though, hence needing to use the built in one plus a frame TBC (horizontal sync) afterwords in the chain.
Where I'm a bit fuzzy is how a frame synchronizer and a full frame TBC are really different from each other. Typically a frame synchronizer would have a genlock input so that it stores frames in a small buffer so that it releases frames with a timing that is consistent with other video streams so that there are not issues when switching between video sources on a live broadcast. The TBC-1000, for example, says that it's both a digital time base corrector and a frame synchronizer on the front, yet has no input for genlock which I thought was required to call something a "frame synchronizer"?
It could be that a frame synchronizer has such a small buffer and is allowed to stop outputting frames after its buffer has run out as opposed to replaying the last good frame over and over until another good frame does arrive like an ideal frame TBC would. I still think a frame synchronizer requires a genlock input though, otherwise it's just doing "free run" synchronization to its own internal clock and not synchronized to anything other than itself.
Perhaps it could be said that all frame TBCs are Frame Synchronizers (if you ignore the absence of genlock input thing and are ok with synchronization to its own internal clock to still be "synchronization"), but not all Frame Synchronizers are frame TBCs.
Seems like a frame synchronizer without a genlock input would be more appropriately termed a "frame rate stabilizer"
Frame TBCs would then be "frame rate stabilizers with more buffering that replay of the last good frame if video drops out"Last edited by aramkolt; 9th Mar 2024 at 10:47.
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Frame syncs don't buffer and release timed. It's realtime attempt to clock, and either fails or bakes in errors.
Typically a frame synchronizer would have a genlock input
so that it stores frames in a small buffer so that it releases frames with a timing that is consistent with other video streams so that there are not issues when switching between video sources on a live broadcast.
yet has no input for genlock which I thought was required to call something a "frame synchronizer"?
It could be that a frame synchronizer has such a small buffer
and is allowed to stop outputting frames after its buffer has run out as opposed to replaying the last good frame over and over until another good frame does arrive like an ideal frame TBC would.
I still think a frame synchronizer requires a genlock input though,
otherwise it's just doing "free run" synchronization to its own internal clock and not synchronized to anything other than itself.
Perhaps it could be said that all frame TBCs are Frame Synchronizers
but not all Frame Synchronizers are frame TBCs.
Seems like a frame synchronizer without a genlock input would be more appropriately termed a "frame rate stabilizer"
Frame TBCs would then be "frame rate stabilizers with more buffering that replay of the last good frame if video drops out"
All of this is also overly simplifying how it works.Want my help? Ask here! (not via PM!)
FAQs: Best Blank Discs • Best TBCs • Best VCRs for capture • Restore VHS -
This is a great comment!
My opinion regarding who would be an authority on terminology: first, it would be the inventor of a new device, who would say "our new thing solves this problem by doing this, and we call it this". If the name is generic enough and is not patented, then other brands start using it as well, then maybe a standards body defines the term more precisely, then another brand adds new features or combines several devices into one, and the definition will either require re-definition or will get fuzzier. In either case, it is not up to self-professed Internet pundits to invent terms for something that has existed and was used for a long time.
Regarding TBC and frame synchronizer. These were two different things at the beginning. TBC dealt with HSync, its memory could hold less than two lines. Frame synchronizer was invented later and dealt primarily with VSync, syncing one more more videos to a reference signal, which could be a plant sync or another video or even a built-in sync generator. Then, as the buffer size in TBCs grew, TBC could handle more and more lines until it could store a whole frame. At this point it could handle frame synchronization too, as well as other things. So, devices with several functions became available. But some of these devices are primarily TBCs, or primarily frame synchronizers, or digital effect consoles, with other functions tacked on simply because the device has a frame-sized buffer, which allow doing all these cool things. The implementation of these tacked-on featured differ.
Your understanding of the TBC-1000 being a "free-run" synchronizer is in sync with my understandingIt syncs just one input signal to a built-in sync generator, so from the point of view of this signal it is a frame synchronizer, although there are no other signals to switch to. DataVideo advertised their device as "Single Channel Full Frame TBC", which is also a "full frame synchronizer". A different name like "frame rate stabilizer" could be invented for such "free-run" synchronizers. It needs a clear definition and it needs to be accepted by the industry.
Last edited by Bwaak; 9th Mar 2024 at 12:30. Reason: frame buffer -> frame synchronizer
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A TBC digitizes an analog signal and processes it is about the only general term you can slap on a TBC. The processing part is manufacturer/industry implementation tailored to fulfill the need it was designed for. Processing could include one, more, or a combination of the following: (H/V) blanking intervals tracking and amplification or regeneration, DOC, line/field/frame store, synchronization, Audio lock. Additional processing tasks that some manufactures do consider part of the TBC such as luma and/or chroma DNR, format conversion, AR/cropping, resizing/upscaling, conversion to analog (CVBS, YC, YCbCr).
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You keep trying to cram everything in tidy boxes, and get things wrong as a result.
Listen to me, dellsam34, etc. It's a very loose term. It as never clearly defined, and never will be. We have to define "what is TBC" within our strict confines (consumer SD analog videotapes), which I've done for 20+ years now.
If people listen to you too closely, it will have two outcomes:
- They get f'd over buying the wrong thing. I've seen this for decades now.
- You will likely screw yourself over at some point, too sure of yourself. And I've seen this happen many times as well.
Again, I've now been doing this for over 30 years. You're reading history. I was living it.
Just today, I finally unsubscribed from a Youtube channel, because the guy gets too much stuff wrong (and it's about Marvel comics, of all things). Simple stuff, too.
I can appreciate that you're trying to learn here. But you're a student, not the teacher.
Want my help? Ask here! (not via PM!)
FAQs: Best Blank Discs • Best TBCs • Best VCRs for capture • Restore VHS -
Time base corrector corrects time base errors by regenerating sync pulses, ensuring their periodicity within certain margins. Time base errors are the periodicity errors of synchronization pulses. Time base is the timing reference to which the sync pulses are synchronized.
TBC was invented to solve a particular problem, so its functionality had been known and advertised. Live broadcast, as well as a recording from a 2-inch VTR was sync'd well enough, but helical machines could not achieve the needed level of precision, making the video recorded with these machines not broadcastable. Digital time base corrector, introduced in 1973, solved this issue.
Sure. But the core task of a TBC has remained the same. -
No, not all of them, Only certain TBCs regenerate sync pulses, Most broadcast TBCs which you like to talk about too much don't regenerate anything, They just re-time the sync pulses based on an internal clock or based on an external sync pulse generator with a delay of a field or a frame. Again this topic is very gray and you have to have an extensive experience in all levels of signal processing hardware to be able to categorize these things and put descriptions of what they do.
In consumer tape formats and VCRs/camcorders, we have basic terms that can be easily understood, Line TBC fixes line timing, frame TBC fixes frame timing, There are certain devices that combine a little bit of both, Not sure why you want to include an entire industry of broadcasting and production into this? -
There is nothing gray regarding the primary function of a TBC. Additional functionality is a gray area, I agree.
Anyway, I just wanted to post a link to a video. I posted definitions from one reputable source for reference. I plan to add definitions from other sources later, so readers can compare them. Some people, who are neither developers of these devices nor a standards body, try to make it more complicated than it is, inventing their own terms in the process. I don't know about you, but I trust manufacturers and standards bodies when I am looking for definitions. -
I'm not against that, What I would really like to see is discussion about testing of actual hardware and comparison that are relevant and beneficial to the members who visit. Definitions are just words on paper, they don't accomplish anything.
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Absolutely! Yesterday I uploaded samples from Panasonic DMR-ES35V, comparing the results to my camcorder that has built-in TBC.
Definition are useful if one wants to have a meaningful conversation without explaining each and every word (and even this does not always help). Definitions are also useful for searching. -
Originally Posted by Bwaak
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What difference does it make, @Alwyn? You haven't watched it anyway
Here is some more trivia for everyone's amusement. The editor-in-chief of this publication wrote over 30 books on technical topics, he was editorial director and associate publisher of Broadcast Engineering and Video Systems magazines, and he held the position of the ATSC’s Vice President of Standards Development until at least 2020. -
Originally Posted by Bwaak
One of the reasons I haven't watched it... -
It's 100% him. He has multiple usernames. We're not fooled.
My problem is that he gets "too big for his britches" (aka, puts on "his big boy pants"), when it comes to multiple topics. TBCs is just the latest area of sudden "expertise".
- Learning is fine, great!
- Trying to be the teacher while you're still a green newbie student is not.
- Know your role.
Especially when it's extremely obvious (to those of us that do understand this topic) that he does not yet understand the topic.
FYI, trying to put everything in neat tidy boxes is what learners do, to attempt to understand it. And that's fine, that's understandable. That's exactly what is going on here. But the pigheaded insistence that it "must" fit into the boxes reveals character, and the lack of ability to truly grasp any topic, as nothing in this world is ever so neat and tidy. The world is complex.
If you understood how these documents actually came into being, you'd never say such silly things. These documents are not religious texts, where people pour over every word to find meaning. And yet, that's what you're doing here. It's ridiculous.
And I read BE cover-to-cover, every issue, for at least 15 years there. How many did you read? I have a lot of page rips still in folders, especially the meaty stuff on encoding algorithms.
My point here is that you're not conversing with other newbies in this thread.Last edited by lordsmurf; 11th Mar 2024 at 01:43.
Want my help? Ask here! (not via PM!)
FAQs: Best Blank Discs • Best TBCs • Best VCRs for capture • Restore VHS -
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Line-TBC (DVD Recorder in passthrough) in action:
Picture 1) shows the signal at the VCR composite output, no TBC. One can see the distorted and fuzzy sync pulses, especially the 2nd pulse on the right.
Picture 2) shows the Y-wire output of the Panny DMR-ES15 in passthrough: Clean and rock stable re-timed sync pulses.
(Note: It's not the same scanline of the picture, but this doesn't matter for this purpose). -
Sharc, can you post the set-up of the measurement to understand the contest? It is not clear to me how to refer to the "line" operation, rather than the "inter-lines" or "frame" behaviour.
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I take shots of analog scanlines of a PAL video signal using an oscilloscope, to demonstrate the horizontal (line-)sync pulse cleanup which a DVD recorder introduces in passthrough.
The pictures show one full scanline plus the next sync pulse indicating the start of the next scanline.
Picture 1) is taken from the Composite (yellow RCA) output of the VCR player, playing a type which was in mediocre-poor condition. Important for a wobbling-free picture are clean and timely precise sync pulses. For a proper horizontal line synchronization (no wobbling, no wiggling, no flagging) the sync pulses need to be stable and clean, as these pulses serve as the reference for a scanline start. Apparently the VCR did not deliver clean and well defined pulses at its output (typical for VHS without TBC). They may vary from scanline to scanline with respect to shape and timing accuracy (jitter), hence the picture would be wobbly (flagging, jitter).
So Picture 1) shows the analog VHS Composite signal (out of the VCR player) which is connected to the Composite input (in) of the DMR-ES15. The first sync pulse is quite ok but the subsequent pulse on the right is 'dirty' and distorted.
The ES15, using its internal signal processing (including re-timing, comb filtering...), eventually delivers clean and well-defined, re-timed line sync pulses at its S-Video output.
Picture 2) is taken from the Y-wire (luma+sync) of the S-video output of the ES15. The sync pulses are now clean and stable (shape, duration, equidistant timing) which prevents line jitter (flagging, wiggle). This clean and stable signal is now connected to the input of the capture device (DATA I-O GV USB2, Hauppauge USB live2, .... whatever).
So the cleanup and reconditioning of the sync pulses which is essential for a horizontally wiggle- and jitter free picture is demonstrated. Some call this functionality - as provided by recommended Panasonic DVD recorders in passthrough - "line-TBC". (I don't want to start a new tug of war about definitions and semantics ...)
(Similar may be demonstrated for "full TBC" functionality for stabilizing the vertical sync for frames as well).Last edited by Sharc; 11th Mar 2024 at 05:11.
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The pictures show one full scanline plus the next sync pulse indicating the start of the next scanline.
as provided by recommended Panasonic DVD recorders in passthrough - "line-TBC". (I don't want to start a new tug of war about definitions and semantics ... ) -
Is ConsumerDV really Bwaak or is this just another trolling topic ?
None can prove and Bwaak can hardly admit it. And even if he admits it is right that a banned member be allowed back under another ID or more (if one of the replies on here was another alias since he was quick enough to praise the comment) ?
Go on on Bwaak. Report me. Like I said in my only reply to this before now. IDGAS.
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