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Old 25th February 2002, 15:43   #1  |  Link
FakerZ
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Maximum bitrate question

I found in some SVCD guides that max video svcd bitrate is 2600, and in a thread posted here (can't remember wich one) I saw something about a 2350 (or something approaching) max bitrate !

What's the real max video bitrate for an SVCD ?
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Old 25th February 2002, 16:04   #2  |  Link
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it really depends on your stand alone player. you can check vcdhelp.com to see what's known about yours.

2600 sounds more like max total bitrate
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Old 25th February 2002, 16:09   #3  |  Link
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Then I should use 2600-128=2472 if I encode audio at 128 ?
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Old 25th February 2002, 16:16   #4  |  Link
da franksta
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if your player can handle 2600 the answer is yes
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Old 25th February 2002, 16:20   #5  |  Link
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Thanks
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Old 25th February 2002, 18:03   #6  |  Link
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hey dude...2600max for an SVCD player...do you have an SVCD player?

I'm sure you have a DVD player can handle MUCH more than 2600Kbps, now if someone would only anser question 2 of my thread a couple days ago:
http://forum.doom9.org/showthread.php?s=&threadid=17979
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Old 25th February 2002, 18:18   #7  |  Link
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No, I don't have an SVCD player, but bitrate issues can cause playback problems (you should know, because it's what happened you when you tried using a 8000 bitrate as you said in your thread).
I just want to stay compliant with the standard so my SVCD will play correctly on most players.
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Old 25th February 2002, 18:31   #8  |  Link
poopity poop
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yeah I did try 4500Kbps and that worked well, I just know the maximum for the DVD player and prolly most will be somewhere in that range
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Old 25th February 2002, 19:37   #9  |  Link
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Max bitrate as described in the standard of SVCD has some "flavors":

maximum VIDEO ALONE is 2600
maxumum AUDIO ALONE (all audio streams combined) is 384
Maximum TOTAL (audio+video+subtitles+whatever) is 2748

if your audio is at 224, your video can be as high as 2524, but since in multiplexing some space (-> bitrate) is wasted, it is slightly lower (perhaps 2510...). You can calculate the exact value with the utility "FitCD" that you can download from doom9.org

if your audio is at 112, your video could be at 2636, but since the video cannot be higher than 2600, that is the maximum.

If you want to have 2 audio streams at 224, bad luck, because you cannot: 224+224=448; maximum for audio is 384. It can be 224+160, or 192+192 or many other combinations, but 224+224 is forbidden.

Of course, all that is what the standard says... I think, unless you have some very specific reasons, you should stick to the standard; some players cannot reach the standard, but that are players that should be avoided. Your encodes should not be handicapped because somewhere in the world some guy has a junk player that can only reach 2000Kbps bitrate maximum, don't you think?

And also, you should not go further than the standard, perhaps the player you have today can play to 3000Kbps, but many other cannot; the standard exists precisely to have a common ground for everyone.

Last edited by Pko; 25th February 2002 at 19:41.
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Old 25th February 2002, 19:45   #10  |  Link
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THAT IS AN ANSWER ! Wow !

Thanks a lot lot lot !!!

I'll save this as a .txt file because it is THE info I needed.

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Old 27th February 2002, 21:47   #11  |  Link
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In regards to having 2 audio streams at 224kbits, I think thats still within the standard. I believe that the max audio bitrate of 384kbits only applies to a single stream.

Svcd standard bitrate limits for both video and audio were derived from the speed at which the data could be read from a cd, ie: 2x. Even if the cd contains audio which adds up to more than 384kbits, its still only playing, in this case, 224kbits of audio at any given time.

I may be completely wrong about this but with 2 audio streams at 224kbits Philips SVCD Verifier still says it complies to the SVCD standard, and I've never found a dvd player which couldn't handle it.

Ultimately I guess it really doesn't matter either way since the svcd standard appears to be anything BUT standard. If it plays on your dvd player than thats really all that matters, just don't go too crazy.
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Old 28th February 2002, 05:20   #12  |  Link
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I looked at a DVD I had with Kenshin on it and did some math:
For a 23 minute episode the entire vob's were 1500mb/episode
With that plugged into DV tool with two audio sources it came out to around 7000Kbps, so that means most DVD players can go at least that high. It would stand to reason that it would be able to read SVCD's at that high, or at least above 4000 which makes SVCD's look perfect.
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Old 28th February 2002, 09:23   #13  |  Link
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when using VBR, is that bitrate the maximum average bitrate or the maximum peak bit rate ?

ee.
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Old 28th February 2002, 13:32   #14  |  Link
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Most DVD players can't read CDR as fast as DVD. The entire laser mechanism is tuned (mechanically and optically) to read DVDs. Plus the fact that, at a given angular speed, more data will move under the laser pick on a DVD than on a CDR.

So, bottom line, few DVD players will be able read 9.8 mbps from CRD, and many won't even read 4.0 mbps (I know my apex won't - I can't even do 3.0 mbps reliably).

@ebert - I believe it is the maximum that you need to worry about for playability. If the max goes above what your player can read (except for maybe very short bursts), you'll get playback problems.
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Old 28th February 2002, 14:14   #15  |  Link
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Quote:
Originally posted by adam
In regards to having 2 audio streams at 224kbits, I think thats still within the standard. I believe that the max audio bitrate of 384kbits only applies to a single stream.
I do not think so... maximum bitrate of an MPEG-I layer 2 stream is 320kbps... Nothing related to SVCD, is just a limitation imposed by the MPEG standards definition... So, it will not have any meaning to say that the stream in SVCD cannot be higher than 384 when in fact it cannot be higher of 320 in any case!

But as you said, if all the players play it, it is a moot point :-)

I think that the audio limitations are not very important, because what SVCD is usually crying for is VIDEO bitrate. For example, the 128 audio is (IMO) usually less annoying than the 2600 video... and 2600 is as high as you can go while 128 is a middle setting.

I've seen professional DVDs that had MP2 at 224 while the video went at 4000-6000! MP2 at 192 is usual in DVB too, and the video there is in the 3000-5000 range.
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Old 28th February 2002, 14:18   #16  |  Link
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I agree with Pko, Video bitrate is THE thing we need to preserve. I almost always encode audio at 112 to gain a few more space for video.
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Old 28th February 2002, 19:07   #17  |  Link
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specs

If you would:
http://www.cdrinfo.com/articles/svcd/
is _the_ link describing the official specs...
In brief: audio: between 64 and 384 kbit/sec, video: up till 2600 kbit/sec, however: total bitrate should not exceed 2.8 Mbit/sec. It'll also explain the whole thing with the svcd scan offsets, and those infamous underflow errors you can get with bbmpeg muxing.
Something I wonder: this document states: audio bitrate: may vary from frame to frame. Does this mean you can create variable bitrate audio for svcd too?
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Old 28th February 2002, 19:20   #18  |  Link
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What does this "underflow error" really mean ?
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Old 28th February 2002, 21:00   #19  |  Link
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Quote:
Originally posted by FakerZ
What does this "underflow error" really mean ?
From the above pages:

Quote:
Synchronization among the Elementary streams is accomplished with Presentation Time Stamps (PTS) in the Program Stream in reference to a common System Clock Reference (SCR). These time-stamps describe the delivery time instances of when a pack is taken from the track buffer and payload is extracted and placed into the decoder which is associated with the packet ID.
svcd consists of at least 2 streams: 1 video and 1 audio. Presentation time stamps in the stream make sure they're played back in sync. (Makes you wonder how standards-compliant nero's svcd mode can really be, seeing as many people are having trouble creating sync'ed svcd's with nero.)A pts underflow means, therefore, that the audio cannot keep up with the video. I usually find that this is the result of a too-high video bitrate.
I usually encode with cce and find that when I set a certain bitrate as maximum, after checking it with bitrate viewer the stream almost always exceeds this maximum by a quite big amount during complex scenes. Thus, I keep my max bitrate setting at 2400 maximum. This way it almost never goes above 2600...
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Old 1st March 2002, 15:01   #20  |  Link
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Re: specs

Quote:
Originally posted by trott
If you would:
http://www.cdrinfo.com/articles/svcd/
is _the_ link describing the official specs...
In brief: audio: between 64 and 384 kbit/sec, video: up till 2600 kbit/sec, however: total bitrate should not exceed 2.8 Mbit/sec. It'll also explain the whole thing with the svcd scan offsets, and those infamous underflow errors you can get with bbmpeg muxing.
Something I wonder: this document states: audio bitrate: may vary from frame to frame. Does this mean you can create variable bitrate audio for svcd too?
There has been some discussion about this recently here at the forums; I think that means exactly that, that VBR audio is allowed, but it is not 100% clear yet... Also there is the much more complex question of, even if it is standard, the actual stand alone players will support it OK (subtitles is standard, but support is sparse and highly variable).

I plan to do some tests soon. I'm also planning to do some new SVCD tests disks with "advanced" features:

- VBR audio
- Subtitles (SVCD, CVD and both mixed)
- Silent HQ still menues, HQ still menus with sound, moving menus
- Chapters
- Mixed PAL/NTSC/FILM streams
- Non-compliant streams (352x480/576, 48KHz audio, peaks going over standard)

The idea is have some SVCD images to test, so people can download them and report what works and what not (something like "svcdtest3, second stream works, third stream does not on player brand XXXXX model YYY"). So there would be a common ground to compare everything.

One of the things that stops me from preparing them is that I need some decent quality source videos/audios that must be totally copyright free...
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