[Ffmpeg-devel] Buffering audio data in case of overflow

Cyril Zorin cyril.zorin
Sat May 6 17:58:46 CEST 2006

On 6-May-06, at 11:40 AM, Mike Melanson wrote:

> Cyril Zorin wrote:
>> Hullo,
>> I'm working on a decoder where the source media format provides  
>> more  than a frame's worth of audio with a frame chunk. In other  
>> words, an  incoming "frame", which is composed of audio and video,  
>> will have  __one__ video frame's worth of data, but potentially N  
>> audio frames'  worth of audio. This means that I can't quite push  
>> it all to ffmpeg,  because ffmpeg defines  
>> How is this situation generally handled? Are there any existing   
>> codecs that need to solve this problem? Right now I'm thinking to   
>> manually buffer the audio, but perhaps there's a better way?
> Does the first decoded audio frame contain more than 192000 bytes  
> (AVCODEC_MAX_AUDIO_FRAME_SIZE) in total? That can handle more than  
> 2 seconds of CD-
Yes, at least the stereo streams. A common "first audio frame"  
payload is about 294,000 bytes (for both channels).
> standard audio. But if so, that requires special handling.
> It is not uncommon for a file to contain a prebuffer for 0.5-1  
> second of audio data to correspond to the first video frame. The  
> way to handle this is to set the frame timestamps correctly and  
> send them to the playback engine. The playback engine worries about  
> keeping the sync. Note that ffplay is not the most reliable program  
> for keeping sync, though.
> -- 
> 	-Mike Melanson
> _______________________________________________
> ffmpeg-devel mailing list
> ffmpeg-devel at mplayerhq.hu
> http://mplayerhq.hu/mailman/listinfo/ffmpeg-devel

More information about the ffmpeg-devel mailing list