[vlc] can't transcode and display

[Angus McMorland]

Thanks gonzague,

On 25 June 2011 14:50, gonzague <gonzagueddr at gmail.com> wrote:
> Hi, It is happening sometime that ffmpeg is not fully effective.
> To know the muxers you can use, type "ffpmeg -formats" , and check the 1rst
> letters ( E=encode, D=decode, A=audio, V=video)
> Same things to know the codecs you can use , typing "ffpmeg -codecs".

I don't think the muxer itself is the problem, since the transcoding
does work on its own. It only doesn't work when I also display the
output. In any case, the page you suggest, shows that transcoding
should work with linux, and the mp4/mp4v combination should be
compatible.

Can anyone suggest how I debug this?

Thanks,

Angus.

> Check compatybility for sout on
> http://www.videolan.org/streaming-features.html
>
>
> On 24/06/2011 23:08, Angus McMorland wrote:
>>
>> Hi all,
>>
>> I'm trying to achieve something that I think should be relatively
>> simple: capturing from a webcam, transcoding to a compressed movie
>> file, and displaying on the screen. I can get the transcoding or the
>> display to work independently, but not together. I can also achieve
>> displaying and saving, without transcoding, into a .avi muxer.
>>
>> I'm calling vlc with the following script:
>>
>> SESSION=quack
>> SAVEDIR=/tmp
>> VIDEV=v4l2:///dev/video0
>>
>> DST_DSP=display{noaudio}
>>
>> #DST_MP4=transcode{vcodec=mp4v,scale=1,vb=2048,vt=80000,size=1920x1080,fps=25}:standard{mux=mp4,access=file,dst=${SAVEDIR}/${SESSION}.mp4,noaudio}
>>
>> DST_MP4=transcode{vcodec=mp4v}:standard{mux=mp4,access=file,dst=${SAVEDIR}/${SESSION}.mp4,noaudio}
>> DST_AVI=std{mux=avi,access=file,dst=${SAVEDIR}/${SESSION}.avi}
>>
>> #SOUT='#duplicate{dst="'${DST_AVI}'"}'  # config 1
>> #SOUT='#duplicate{dst="'${DST_MP4}'"}' # config 2
>> #SOUT='#duplicate{dst="'${DST_DSP}'",dst="'${DST_MP4}'"}' # config 3
>> SOUT='#duplicate{dst="'${DST_DSP}'",dst="'${DST_AVI}'"}' # config 4
>>
>> vlc -vvv --one-instance ${VIDEV} --v4l-caching 1024 --sout=${SOUT}
>> --no-sout-audio&
>>
>> where using the SOUT lines for configs 1, 2 and 4 work as expected,
>> but the one I want, config 3, doesn't. Instead, it creates the .mp4
>> file, but doesn't write into it, and error messages are printed to
>> stdout like:
>>
>> [0x12a58a0] stream_out_transcode stream out debug: late picture skipped
>> (1017)
>>
>> I'm running a x86_64 quad core 2.7 GHz Intel machine with 8 GB of RAM,
>> so I guess I'll be surprised if the hardware just isn't up to it.
>> There's no appreciable CPU load when I'm trying any of these config
>> modes.
>>
>> Please can anyone tell me what I'm doing wrong?
>>
>> Thanks,
>>
>> Angus
>
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-- 
AJC McMorland
Post-doctoral research fellow
Neurobiology, University of Pittsburgh