[FFmpeg-devel] allocate enough memory for full audio frame in ffmpeg.c

[Justin Ruggles]

Michael Niedermayer wrote:

> On Sun, Jun 06, 2010 at 11:41:14AM -0400, Justin Ruggles wrote:
>> Hi,
>>
>> This patch fixes part of Issue 1921.
>>
>> do_audio_out() in ffmpeg.c reads samples from the input to a FIFO until
>> it has enough for a full output frame, then reads from that FIFO to
>> audio_buf for encoding.  do_audio_out() is called for each input packet,
>> and the allocated size of audio_buf is based on each single packet.
>> However, it often takes multiple calls of do_audio_out() to fill the
>> FIFO enough to encode a single output frame, so sometimes audio_buf is
>> not large enough.  This patch ensures that audio_buf is large enough
>> before reading from the FIFO.
>>
>> This still doesn't fix the FLAC encoder part of Issue 1921, but that is
>> a separate issue really.  The FLAC encoder is lazy and requires a large
>> output buffer instead of checking the remaining buffer size before every
>> write.
>>
>> -Justin
>>
> 
>>  ffmpeg.c |    9 +++++++++
>>  1 file changed, 9 insertions(+)
>> 34c8e17759394eaba1c8c60f85b226de8f9e5d4c  audio_buf_size.patch
>> Index: ffmpeg.c
>> ===================================================================
>> --- ffmpeg.c	(revision 23504)
>> +++ ffmpeg.c	(working copy)
>> @@ -962,6 +962,15 @@
>>              AVPacket pkt;
>>              av_init_packet(&pkt);
>>  
>> +            /* make sure audio_buf is large enough to hold the frame */
>> +            if (allocated_audio_buf_size < frame_bytes) {
>> +                av_fast_malloc(&audio_buf, &allocated_audio_buf_size, frame_bytes);
> 
> cant this size be considered where we allocate the buffer?

Yeah, that sounds better.  New patch attached.  This patch also changes
the last small frame encoding to also read the remaining FIFO data to
audio_buf, for the same reason.

Thanks,
Justin

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