[FFmpeg-devel] [PATCH] Fixes avcodec_find_best_pix_fmt() with more than 64 pix fmts defined

Matthew Einhorn moiein2000 at gmail.com
Fri Aug 26 19:08:48 CEST 2011


On Fri, Aug 26, 2011 at 12:32 PM, Matthew Einhorn <moiein2000 at gmail.com> wrote:
> On Fri, Aug 26, 2011 at 12:10 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> On Sun, Aug 21, 2011 at 04:19:14PM -0400, Matthew Einhorn wrote:
>>> On Sun, Aug 21, 2011 at 2:56 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> [...]
>>> ---
>>>  libavcodec/avcodec.h    |   34 ++++++++++++++++++++++++++++++++
>>>  libavcodec/imgconvert.c |   49 ++++++++++++++++++++++++++++++++++------------
>>>  2 files changed, 70 insertions(+), 13 deletions(-)
>>>
>>> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
>>> index 4f0ed2d..6578d5d 100644
>>> --- a/libavcodec/avcodec.h
>>> +++ b/libavcodec/avcodec.h
>>> @@ -3511,6 +3511,40 @@ int avcodec_get_pix_fmt_loss(enum PixelFormat dst_pix_fmt, enum PixelFormat src_
>>>  enum PixelFormat avcodec_find_best_pix_fmt(int64_t pix_fmt_mask, enum PixelFormat src_pix_fmt,
>>>                                int has_alpha, int *loss_ptr);
>>>
>>> +/**
>>> + * Find the best pixel format to convert to given a certain source pixel
>>> + * format and a selection of two destination pixel formats. When converting from
>>> + * one pixel format to another, information loss may occur.  For example, when converting
>>> + * from RGB24 to GRAY, the color information will be lost. Similarly, other losses occur when
>>> + * converting from some formats to other formats. avcodec_find_best_pix_fmt2() selects which of
>>> + * the given pixel formats should be used to suffer the least amount of loss.
>>> + *
>>> + * If one of the destination formats is PIX_FMT_NONE the other pixel format (if valid) will be
>>
>>> + * returned. If two destination pixel formats have similar losses, the one with smallest
>>> + * average bit depth will be chosen.
>>
>> It is probably better not to restrict the API this way
>
> How else should I chose from two fmts with identical loss? Or should I
> return any one of them, or PIX_FMT_NONE? The old function did it this
> way (returned the one with smallest loss). Or did you mean about
> PIX_FMT_NONE.

Never mind,  think I understand. Remove it from the API but have the
function still do it this way. Fixed in attached.
>>
>>
>>> + *
>>> + * @code
>>> + * src_pix_fmt = PIX_FMT_YUV420P;
>>> + * dst_pix_fmt1= PIX_FMT_RGB24;
>>> + * dst_pix_fmt2= PIX_FMT_GRAY8;
>>> + * dst_pix_fmt3= PIX_FMT_RGB8;
>>> + * loss= FF_LOSS_CHROMA; // don't care about chroma loss, so chroma loss will be ignored.
>>> + * dst_pix_fmt = avcodec_find_best_pix_fmt2(dst_pix_fmt1, dst_pix_fmt2, src_pix_fmt, alpha, &loss);
>>> + * dst_pix_fmt = avcodec_find_best_pix_fmt2(dst_pix_fmt, dst_pix_fmt3, src_pix_fmt, alpha, &loss);
>>> + * @endcode
>>> + *
>>> + * @param[in] dst_pix_fmt1 One of the two destination pixel formats to choose from
>>> + * @param[in] dst_pix_fmt2 The other of the two destination pixel formats to choose from
>>> + * @param[in] src_pix_fmt Source pixel format
>>> + * @param[in] has_alpha Whether the source pixel format alpha channel is used.
>>> + * @param[in, out] loss_ptr Combination of loss flags. In: selects which of the losses to ignore, i.e.
>>> + *                               NULL or value of zero means we care about all losses. Out: the loss
>>> + *                               that occurs when converting from src to selected dst pixel format.
>>> + * @return The best pixel format to convert to or -1 if none was found.
>>> + */
>>> +enum PixelFormat avcodec_find_best_pix_fmt2(enum PixelFormat dst_pix_fmt1, enum PixelFormat dst_pix_fmt2,
>>> +                                            enum PixelFormat src_pix_fmt, int has_alpha, int *loss_ptr)
>>> +
>>>  #define FF_ALPHA_TRANSP       0x0001 /* image has some totally transparent pixels */
>>
>> this doesnt compile
> Sorry, forgot the semicolon. Will fix it.
>
> Thanks,Matt
>

I'm also re-attaching the patch to remove the unused "find best pix
fmt1" function from my previous email for easier access.

Thanks for your patience,
Matt
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0001-Adds-a-new-pix-fmt-function-that-selects-the-best-de.patch
Type: application/octet-stream
Size: 6696 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20110826/0cd08700/attachment.obj>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: 0002-Removes-the-internal-avcodec_find_best_pix_fmt1-func.patch
Type: application/octet-stream
Size: 1842 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20110826/0cd08700/attachment-0001.obj>


More information about the ffmpeg-devel mailing list