[FFmpeg-devel] [PATCH] Fixes avcodec_find_best_pix_fmt() with more than 64 pix fmts defined
Matthew Einhorn
moiein2000 at gmail.com
Sat Aug 27 03:52:40 CEST 2011
On Fri, Aug 26, 2011 at 7:00 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Fri, Aug 26, 2011 at 01:08:48PM -0400, Matthew Einhorn wrote:
>> 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.
>
> it seems this one doesnt apply cleanly anymore
I'm attaching the same patch regenerated from a clean git branch. Not
sure why the previous one didn't work.
Thanks,
Matt
>
>
> [...]
>> avcodec.h | 33 +++++++++++++++++++++++++++++++++
>> imgconvert.c | 49 ++++++++++++++++++++++++++++++++++++-------------
>> 2 files changed, 69 insertions(+), 13 deletions(-)
>> 95413805a93e6eb4da46b290a0b64eec7f140771 0001-Adds-a-new-pix-fmt-function-that-selects-the-best-de.patch
>> From 7e215a4324bbfeed65a04313014d44df5c4dc29c Mon Sep 17 00:00:00 2001
>> From: Matthew Einhorn <moiein2000 at gmail.com>
>> Date: Fri, 26 Aug 2011 13:03:50 -0400
>> Subject: [PATCH] Adds a new pix fmt function that selects the best dest fmt
>> from among 2 formats to convert to, given a certain src
>> format.
>>
>> Similar to avcodec_find_best_pix_fmt(), but instead only compares two destination
>> pix fmts and selects one of these fmts as the best dest format when converting from
>> a given source format. Also, as opposed to avcodec_find_best_pix_fmt() which supports
>> only the first 64 defined pixel formats, this supports as input any of the defined
>> pixel formats.
>>
>> Also replaces the old function to rely on the new function.
>
> applied, thanks
>
> [...]
>
> --
> Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> No snowflake in an avalanche ever feels responsible. -- Voltaire
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