[FFmpeg-cvslog] r19091 - trunk/libavcodec/4xm.c

Baptiste Coudurier baptiste.coudurier
Sat Jun 6 10:49:35 CEST 2009

Baptiste Coudurier wrote:
> On 6/5/2009 2:25 PM, Michael Niedermayer wrote:
>> On Fri, Jun 05, 2009 at 02:09:05PM -0700, Baptiste Coudurier wrote:
>>> On 6/5/2009 1:10 PM, Michael Niedermayer wrote:
>>>> On Fri, Jun 05, 2009 at 10:12:14AM +0200, bcoudurier wrote:
>>>>> Author: bcoudurier
>>>>> Date: Fri Jun  5 10:12:14 2009
>>>>> New Revision: 19091
>>>>> Log:
>>>>> 4xm decoder uses get_buffer, set CODEC_CAP_DR1
>>>> i think you broke several decoders with these changes, no i dont
>>>> know which but
>>>> CODEC_CAP_DR1 does not just mean the codec uses get_buffer()
>>>> but it means it works with any get_buffer() implementation while
>>>> lack of CODEC_CAP_DR1 means it requires the libavcodec internal get_buffer()
>>> Interesting, I did misunderstand the Doxygen then:
>>> /**
>>>  * Codec uses get_buffer() for allocating buffers.
>>>  * direct rendering method 1
>>>  */
>>> #define CODEC_CAP_DR1             0x0002
>>>> one case (that applies to 4xm IIRC) is that linesize == width*bpp is required
>>>> by some decoders
>>> Well, user can override the function in any case, so decoder must not
>>> use get_buffer in AVCodecContext IMHO.
>> hmm, the original idea i think was that the user would not override
>> get_buffer when CODEC_CAP_DR1 is not set but it seems not documented
>> anywhere, this is of course not good
>> we either could fix the docs and call everyone who overrides get_buffer
>> without a CODEC_CAP_DR1 buggy
>> or
>> change decoders to not use (re)get_buffer/release_buffer but the default
>> code directly
>> IMHO, because overriding get_buffer without a set CODEC_CAP_DR1 always was
>> buggy i think user apps should be fixed that do this
>> I mean even if we change codecs to use default_*buffer() directly, user apps
>> would still fail to work with old libavcodec
>> thus IMHO this is a bug in the docs not the code
> IMHO, codecs should be updated to use avcodec_default_get_buffer
> directly which will avoid confusion.

Well, I need to revise my statement. Doing that for old codecs this
might have weird effects for users already overriding get_buffer,
example the old way of setting pts used by ffplay, I think many
applications did that unfortunately and ffplay didn't check for

> [...]
> I'll check decoders and revert/modify them on a per case basis once we
> settled this.

Btw, If I understood correctly how this works, here is a patch for 4xm
decoder which should use reget_buffer.

Baptiste COUDURIER                              GnuPG Key Id: 0x5C1ABAAA
Key fingerprint                 8D77134D20CC9220201FC5DB0AC9325C5C1ABAAA
FFmpeg maintainer                                  http://www.ffmpeg.org
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 4xm_reget.patch
Type: text/x-diff
Size: 825 bytes
Desc: not available
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-cvslog/attachments/20090606/47bbf250/attachment.patch>

More information about the ffmpeg-cvslog mailing list