[FFmpeg-devel] [PATCH] Set correct frame_size for Speex decoding

Justin Ruggles justin.ruggles
Sat Aug 1 12:53:11 CEST 2009

Michael Niedermayer wrote:
> On Fri, Jul 31, 2009 at 07:34:00PM -0400, Justin Ruggles wrote:
>> Michael Niedermayer wrote:
>>> On Fri, Jul 31, 2009 at 06:48:59PM -0400, Justin Ruggles wrote:
>>>> Michael Niedermayer wrote:
>>>>> On Thu, Jul 30, 2009 at 07:25:17PM -0400, Justin Ruggles wrote:
>>>>>> Justin Ruggles wrote:
>>>>>>> Hi,
>>>>>>> Currently AVCodecContext.frame_size is not set correctly for Speex.
>>>>>>> Since the Ogg and FLV demuxers and the libspeex decoder handle a full
>>>>>>> packet as a single frame, frame_size should be set to the Speex
>>>>>>> frame_size * frames_per_packet.
>>>>>>> If frames_per_packet is not specified in the Speex header, or if there
>>>>>>> is no header, it can be determined after decoding the first packet.
>>>>>>> Stream copy is not implemented yet for Speex, but once it is, a parser
>>>>>>> will be able to set all the stream parameters instead of the decoder
>>>>>>> when the header is missing or incomplete.
>>>>>> ping.
>>>>> it might be helpfull if you say who you expect to review this
>>>> In general, I'm looking for an ok on having lavf and lavc treat a whole
>>>> Speex packet as a single frame.  After considering and trying to code
>>>> the split-then-join idea it did not seem like a very clean solution, and
>>>> it is not really necessary.  This is my general plan:
>>> which values of frames_per_packet does each container allow?
>>> that is each container that supports speex
>> AFAIK, Ogg is only limited by the Speex header, which supports up to
>> INT32_MAX. (libspeex reads the 4-byte value in the header as a signed int32)
>> For FLV, it's unclear.  Here is a quote from Art:
>>> Here's what I found.  Set the speex frames per packet all the way from 1 up
>>> to 8, and it appears they all now work with Flash Player (I erroneously
>>> reported that 1 would not work before, but at least with the latest version
>>> that is not the case).  Setting 9 frames per packet causes flash player to
>>> start stuttering.  Set 10 or more frames per packet causes flash player to
>>> crash, bringing down the browser with it.
>> The speexenc commandline program allows encoding between 1 and 10 frames
>> per packet.
> so if you have a ogg with 11 -acodec copy to flv will not work, IMO thats a
> bug. How should that be fixed?
> if the parser splits the packets as it should, it should work ...

-acodec copy from Ogg to FLV with 11 frames per packet would work just
fine in FFmpeg, but Flash Player would crash when playing the file.
That seems like a bug in Flash Player to me.

If the parser splits packets, we would also need a way for the user to
tell the muxer to combine frames back together if they so desire,
otherwise we will force the user to accept the large container overhead
that goes along with 1 frame per packet.  I got the splitting to work,
but the combining gave me trouble.  I'm not even sure what the best way
to approach it would be.


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