[Ffmpeg-devel] ffmpeg stderr output

[Michel Bardiaux]

Engin Kurutepe wrote:
> Michael,

!!! Please dont top-post.

Please note: there is a Michel (me) and a Michael (Niedermayer) and 
confusing us is *NOT* going to help!

> 
> I found that av_log_set_level() can be used to set the verbosity of the 
> library.

That API is being deprecated in favor of direct access to the global 
variables.

> 
> after setting maximal verbosity level I found that 
> avcodec_decode_video() is complaining about current_picture_ptr in 
> MpegEncContext being equal to NULL after decoding (from h264.c):
>     
>     if(!s->current_picture_ptr){
>         av_log(h->s.avctx, AV_LOG_DEBUG, "error, NO frame\n");
>         return -1;
>     }

This is indeed a bit confusing. It is conceivable that a codec doesnt 
return a decoded picture if it is waiting for something (eg MPEG after a 
P frame), but that should not be an *error*. So it should be either

av_log(h->s.avctx, AV_LOG_ERROR, "error, NO frame\n");

or

av_log(h->s.avctx, AV_LOG_INFO, "NO frame\n");

But I know very little about h264 so I cant choose.

> 
> This happens when I try to open an h264 stream from a RTSP server. VLC 
> can play the video from the server just fine. I am probably initializing 
> the AVCodecContext wrongly, but this is handled by parsing the SDP 
> description using the sdp_parse() function in rtsp.c.
> 
> Engin.

Cant help you there. Can you read the stream with ffmpeg itself?

> 
> Michel Bardiaux wrote:
>> Engin Kurutepe wrote:
>>> Dear All,
>>>
>>> This is probably a very silly question but couldn't find anything 
>>> through google.
>>>
>>> I'm using avcodec_decode_video() under win xp. it fails and returns 
>>> -1 but doesn't spit out what the error was to stderr. Any ideas what 
>>> might be wrong with av_log()?
>>
>> Maybe there is simply no av_log at that place in the source.
>>
>> What happens if you use ffmpeg.exe itself on the input file?
>>
>>>
>>> how is the verbosity level set for the ffmpeg library? is that 
>>> something that should be done during compile-time or is it possible 
>>> to change it through the api?
>>
>> Change global variable av_log_level
>>
>> Greetings,



-- 
Michel Bardiaux
R&D Director
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