[Libav-user] Unable to find codec

francesco at bltitalia.com francesco at bltitalia.com
Mon Jan 9 15:21:02 CET 2012

I call at start the init and register:

  // Register all formats and codecs

but it seems that the codec aren't registered.  I make an attempt using 


but nothing.  The matter that I don't understand is that in this last case
I should have a valid pointer.  Codec "mpeg2video" is present, so should 
return a valid pointer.  Where is the mistake ?

At 15.04 09/01/2012 +0100, you wrote:
>Le decadi 20 nivôse, an CCXX,
francesco-V8Dg30rvLxeB+jHODAdFcQ at public.gmane.org a écrit :
>> I compiled last release of ffmpeg with all codecs enabled. So I linked the
>> libraries to my project and opened a simple image composed with a single
>> The av_open_input_file, and av_find_stream_info(pFormatCtx) works correctly,
>> that is info contained into pFormatCtx are correct (video stream is a MPEG2
>> one).The problem arises when I attempt to detect codec.  Here is the code:
>>   videoStream=-1;
>>   for(i=0; i<pFormatCtx->nb_streams; i++)
>>     if(pFormatCtx->streams[i]->codec->codec_type==AVMEDIA_TYPE_VIDEO) {
>>       videoStream=i; break;
>>     }
>>   if(videoStream==-1) {Memo1->Lines->Add("Unable to detect stream type");
>> goto   end_conv;}
>Note that you can use av_find_best_stream for that.
>>    // Get a pointer to the codec context for the video stream
>>   pCodecCtx=pFormatCtx->streams[videoStream]->codec;
>>   // Find the decoder for the video stream
>>   pCodec=avcodec_find_decoder(pCodecCtx->codec_id);
>> The pCodec is always null.  Did anyone have an idea ?
>Did you forge to call some of the register_all?
>If not, trim your program until remains only the bare minimum to show the
>problem; do not hesitate to hardcode filenames or even codec ids. The result
>should probably be less than 20 lines. Then post it here as a whole.
>  Nicolas George
>Libav-user mailing list
>Libav-user at ffmpeg.org
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*    ing. Francesco  Cuzzocrea
*    company:    BLT Italia srl        web:  http://www.blt.it
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