[vlc-devel] Re: [VLC] VLC with ffmpeg compile + YUV play

Andrea Guzzo xant at xant.net
Sun Jan 23 13:50:36 CET 2005


mmm...
what do you think about using directly the ffplay tool that comes with 
ffmpeg distribution? ...
i think it should be appropriate for your purpose ....

bye,
x.

Il giorno 22/gen/05, alle 17:26, Dusan Mudric ha scritto:

> Find my explanation of our effort inlined. I need a reference to 
> application
> which uses ffmpeg and can run YUV video clips created by ISO. 
> Application
> needs to be open source so we can try our new encoding algorithms.
>
>
> From: "Benjamin PRACHT" <bigben+spam at videolan.org>
>
>> On Thu, Jan 20, 2005, Dusan Mudric wrote :
>>>> Well, for that, the best woulkd certainly be to have a look on one 
>>>> of
>>>> the pages linked here http://developers.videolan.org/vlc/, depending
> on
>>>> the destination architecture.
>>>
>>> [Dusan] Can you be more specific? We spent a lot of  time already on
> this page without success.
>>
>> Well, what are you trying to do exactly ? Which OS ? What is the error
>> / problem you are facing ?
>>
>
> [Dusan] We want to test new DCT, wavelet and motion estimation 
> algorithms in
> VLC codec. To do that we want to find which part of VLC code we need to
> replace. For MPEG4 it is in ffmpeg library. If we change this library, 
> we
> want to run VLC and test our algorithms. We have problem linking 
> ffmpeg with
> VLC. If there is another open source application using ffmpeg library 
> and
> can be used to run YUV video clips, please suggest.
>
> Based on my understaning of VLC, it uses ffmpeg library for encoding
> algorithms. We want to modify MPEG4 encoder:
>
> ffmpeg-20041113\libavcodec\mpegvideo.c(6363):AVCodec mpeg4_encoder = {
> MPV_encode_init, ...}
>
> Where motion is done by:
> =================
> ffmpeg-20041113\libavcodec\mpegvideo.c(4280):    encode_mb(s, motion_x,
> motion_y);
> C:\CYGWIN\VLC\ffmpeg\libavcodec\mpegvideo.c(4121):        
> mpeg4_encode_mb(s,
> s->block, motion_x, motion_y); break;
> C:\CYGWIN\VLC\ffmpeg\libavcodec\h263.c(767):void
> mpeg4_encode_mb(MpegEncContext * s,
>
> and texture:
> ========
> ffmpeg-20041113\libavcodec\mpegvideo.c(4063):
> s->block_last_index[i] = s->dct_quantize(s, s->block[i], i, s->qscale,
> &overflow);       <---- HERE IS DCT done
> C:\CYGWIN\VLC\ffmpeg\libavcodec\mpegvideo.c(5980):static int
> dct_quantize_c(MpegEncContext *s, ..)
>
>
>
>
>>>>
>>>> Well, If the YUV track is encapsulated in a muxing format VLC 
>>>> support
>>>> (well, do we have support for a muxing format that allows raw video
> ?),
>>>> it should work... But I'm not aware of any way to have VLC read any
> raw
>>>> video stream (excepted the particular case of DV streams).
>>>>
>>>
>>> [Dusan] How do you test ffmpeg encoders if VLC doesn't run YUV?
>>>
>>
>> Well, VLC does handle quite a lot of variants of the YUV chromas,
>> What I meant is that I'm not aware of any way to feed VLC with a raw
>> uncompressed YUV stream coming from a file. As I said, raw YUV streams
>> from capture cameras (Video4linux, Directshow, etc) are handled. 
>> Adding
>> support for raw YUV files shouldn't be to hard, I guess. It would be a
>> matter of creating a "raw" demux, that allows to specify the fourcc of
>> the given track, as well as the dimensions of the picture (That might
>> already exist without me being aware of it).
>>
>> Transcoding is mostly used to change the codec/bitrate of a already
>> encoded stream on the fly, before re-streaming it. If your purpose is 
>> to
>> test the quality of the ffmpeg encoders, than VLC certainly isn't the
>> application you are looking for...
>
> [Dusan] Sounds like you know other applications which use ffmpeg and 
> can
> encode/decode ISO reference YUV video clips. Would you mind to tell us 
> which
> application we can use instead?
>
>>
>> --
>> BigBen
>>
>> --
>> This is the vlc-devel mailing-list, see http://www.videolan.org/vlc/
>> To unsubscribe, please read http://developers.videolan.org/lists.html
>>
>>
>
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