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Old 11-09-09, 09:36 PM   #1
latterman
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Question ffodivxvdpau & packed bitstream problem

I checked many .avi files with ffodivxvdpau codec and most of them appeared a frame skipping effect. All those files (at least those i have checked) who came up with that problem had packed bitstream and by converting the stream to unpacked with avidemux solved the problem.

Should we expect the nvidia decoder to accept packed bitstreams in the near future, or should we ask (ffmpeg perhaps ?) for a filter to do an "on the fly" unpacking?

I know that playing a low resolution divx/xvid video file on a modern cpu is not an issue, but if we can through that load to the gpu, why not do it, right?

PS: Unpacking all those old .avi and saving them again, i dont think it will be an option, at least not for everyone.
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Old 11-10-09, 10:44 AM   #2
Stephen Warren
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Default Re: ffodivxvdpau & packed bitstream problem

I need some further investigation to determine whether ffmpeg or the VDPAU driver should solve this.

Do you know any more details re: packed vs. not bitstreams? I can't find anything on Google that explains the low-level bitstream format differences.

Which version of MPlayer are you using right now?

Does MPlayer play these files OK with regular SW decoding?

Can you please upload a sample file to our file drop (please see sticky post for upload details).

Thanks.
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Old 11-10-09, 02:28 PM   #3
cehoyos
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Default Re: ffodivxvdpau & packed bitstream problem

Quote:
Originally Posted by Stephen Warren View Post
I need some further investigation to determine whether ffmpeg or the VDPAU driver should solve this.

Do you know any more details re: packed vs. not bitstreams? I can't find anything on Google that explains the low-level bitstream format differences.
http://guru.multimedia.cx/avi-and-b-frames/
http://thread.gmane.org/gmane.comp.v...31/focus=76644
And grep for divx_packed in libavcodec/h263.c and libavcodec/h263dec.c.
Quote:
Does MPlayer play these files OK with regular SW decoding?
Certainly (with one frame delay).
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Can you please upload a sample file to our file drop (please see sticky post for upload details).
http://samples.mplayerhq.hu/ffmpeg-b...g/packed_b.avi

Carl Eugen
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Old 11-11-09, 08:10 AM   #4
latterman
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Default Re: ffodivxvdpau & packed bitstream problem

Apologies for the delayed response.

I believe Carl Eugen have covered all the questions

The issue with packed bistreams is quite old and -if am not wrong- it came up when standalone dvd-players started playing .avi files.

A nice article about packed bitstream files and playback issues can be found in the next link http://itsjustonesandzeros.blogspot....bitstream.html which describes pretty simple the situation.

If more sample files are needed, i would be more than glad to provide them.

Thank you for your responses, best regards, Dimitris.
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Old 11-12-09, 12:01 PM   #5
Stephen Warren
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Default Re: ffodivxvdpau & packed bitstream problem

I've repro'd the issue with the clip Carl sent.

I originally didn't realize that this was just a frame-dropping issue as opposed to a corruption issue. I suspect the issue is simply that the ffmpeg/VDPAU integration code isn't splitting the "packed" B-frames out into a separate frames, so some B-frames are simply not being decoded and displayed.

I'll file a bug here anyway, to investigate what it'd take to fix this in ffmpeg. Let me know if anyone else starts looking into that so we don't duplicate effort. Thanks.
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Old 11-14-09, 06:07 AM   #6
latterman
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Default Re: ffodivxvdpau & packed bitstream problem

Quote:
Originally Posted by Stephen Warren View Post
I've repro'd the issue with the clip Carl sent.

I originally didn't realize that this was just a frame-dropping issue as opposed to a corruption issue. I suspect the issue is simply that the ffmpeg/VDPAU integration code isn't splitting the "packed" B-frames out into a separate frames, so some B-frames are simply not being decoded and displayed.

I'll file a bug here anyway, to investigate what it'd take to fix this in ffmpeg. Let me know if anyone else starts looking into that so we don't duplicate effort. Thanks.
Stephen, my only intention was to inform you (plural) about the problem and perhaps mention a temporal solution for every average user (like myself). After all, i described the "phenomenon" as a "frame skipping effect" which is close to your "frame-dropping issue".

I came back to this just to clarify my intentions which were not -by far- accusations or any kind of insinuations about "corruption" concerning any party involved.

English is not my native language and my humble opinion is that "corruption" opposed to "just" (mentioned above) was not describing my intentions and i hope that the members/guests of this forum who might read my posts above didn't came to this misconcepted conclusion. If they did, my sincere apologies.

I know that packed-bitstream is called as a dirty hack so maybe will be treated as, but what will happen if someone feed it to vdpau not through ffmpeg? (That i believe in the near future will unpack the stream) (Strictly hypothetical question) Is the video decoder a "stand-alone" hardware decoder or is it more like a software code running on gpu (something like cuda, so changes can be made there)?

I hope my questions are not too naive, after all i am new here. Thank you for your time and for your answers, keep up the good job you are doing, best regards, Dimitris.
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Old 11-16-09, 12:44 AM   #7
AaronP
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Default Re: ffodivxvdpau & packed bitstream problem

Quote:
Originally Posted by latterman View Post
I came back to this just to clarify my intentions which were not -by far- accusations or any kind of insinuations about "corruption" concerning any party involved.

English is not my native language and my humble opinion is that "corruption" opposed to "just" (mentioned above) was not describing my intentions and i hope that the members/guests of this forum who might read my posts above didn't came to this misconcepted conclusion. If they did, my sincere apologies.
In this context, "corruption" means when the screen displays the wrong colors (corruption of the image) as opposed to displaying the correct colors at the wrong time.

Sorry for the misunderstanding! English is hard, I know.
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Old 11-16-09, 03:20 PM   #8
latterman
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Default Re: ffodivxvdpau & packed bitstream problem

Thank you AaronP for your explanation.

Corruption in my language is a strong word, that is why i was so jumpy in my previous post.

As Stephen Warren wrote, this is a frame-dropping issue, none has mentioned anything about wrong colors or any kind of image distortion.

On the other hand, i recently bought a new card with NVIDIA VDPAU Feature Sets C, knowing that the deference with the Feature Sets B cards was the MPEG-4 Part 2 (a.k.a MPEG-4 ASP) hardware decoding, but as much as i have searched there was nowhere any information about the packed bitstream problem. So having that in my back of my head and also reading about that "corruption"... LOL

If i setup windows xp and use dxva, i will have the same dropping frame problem with packed bitstream videos? (I know this is a thread in linux subforum, but what i am actually asking is if this is a software problem regarding linux os or has to do with the hardware).

PS: English sometimes can be hard, i can say that for sure, but also some responses in English can be straight too, so thanks again for your explanation, keep up the good work and i am looking forward for your answers.
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