[Ffmpeg-devel] MPEG-1 Decoder

Matthew Gertner matthew
Thu Sep 29 15:08:17 CEST 2005


Nico,

Yep, MPlayer is able to read the file even when forced to use the ffmpeg 
codecs, which I presume confirms that libavcodec is not at fault, as you 
surmised. If the demuxer is the problem, is there some workaround for 
this? What can I do to make sure that we can decode this type of file?

Cheers,
Matt

Nico Sabbi wrote:

> Matthew Gertner wrote:
>
>> Hi,
>>
>> We're using libavcodec and libavformat in our project to decode 
>> various audio/video formats. I understand that MPEG-1 is supported, 
>> but just came across a video file that the libraries were unable to 
>> interpret. The libavcodec reports a single audio stream in the file 
>> and no video stream. I verified the format using GSpot, and it is 
>> indeed MPEG-1 though I suppose there are many internal variations to 
>> the format (I'm far from an expert on this). I can open and play the 
>> file using VirtualDub and MPlayer, so it definitely is a valid video 
>> file. I know that MPlayer uses libmpeg2 as well as libav*, so based 
>> on this and some vague hints I found, I am speculating that there are 
>> some issues with decoding MPEG-1 using libav*. But I wasn't able to 
>> find any definitive confirmation of this.
>>
>> Can someone help me out? Are there indeed limitations to MPEG-1 
>> support, or am I doing something wrong (wrong configuration flags or 
>> something). In the former case, are there plans to address these 
>> limitations? Is there some timeline? Or should we plan to use 
>> libmpeg2 as well?
>>
>> Thanks in advance,
>> Matt
>>
>
> your problem seems to be due to the mpeg demuxer in libavformat, not 
> from the decoder in libavcodec.
> Many times I experienced the same issue, i.e. when reading raw vcd 
> images.
> To verify it, run
> $ mplayer -vc ffmpeg12 file.mpg
>
>
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