[FFmpeg-devel] [PATCH] Fixes avcodec_find_best_pix_fmt() with more than 64 pix fmts defined
Matthew Einhorn
moiein2000 at gmail.com
Sun Aug 21 22:19:14 CEST 2011
On Sun, Aug 21, 2011 at 2:56 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
> On Sun, Aug 21, 2011 at 02:45:54PM -0400, Matthew Einhorn wrote:
>> On Sun, Aug 21, 2011 at 2:19 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> > On Sun, Aug 21, 2011 at 01:22:09PM -0400, Matthew Einhorn wrote:
>> >> On Sun, Aug 21, 2011 at 12:09 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> >> > On Sat, Aug 20, 2011 at 05:06:45PM -0400, Matthew Einhorn wrote:
>> >> >> On Fri, Aug 19, 2011 at 6:22 PM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> >> >> > On Wed, Aug 17, 2011 at 08:50:50PM -0400, Matthew Einhorn wrote:
>> >> >> >> On Wed, Aug 17, 2011 at 9:32 AM, Michael Niedermayer <michaelni at gmx.at> wrote:
>> >> >> >> > On Wed, Aug 17, 2011 at 10:43:34AM +0200, Stefano Sabatini wrote:
>> >> >> >> >> On date Wednesday 2011-08-17 02:38:37 -0400, Matthew Einhorn encoded:
>> >> >> >> >> > Hi,
>> >> >> >> >> >
>> >> >> >> >> > As stated, this patch (attached) should fix
>> >> >> >> >> > avcodec_find_best_pix_fmt() so that now with more than 64 pix fmts,
>> >> >> >> >> > the function should be able to work for the first 64 fmts. Currently
>> >> >> >> >> > the function returns a bad formats, for example,
>> >> >> >> >> > avcodec_find_best_pix_fmt(1ULL << PIX_FMT_GRAY8, PIX_FMT_YUV420P, 0,
>> >> >> >> >> > &nLoss) returns 72 instead of 8.
>> >> >> >> >> >
>> >> >> >> >> > Please be gentle as this is the first time I used git or submitted a
>> >> >> >> >> > patch. If this works fine I'll try to submit a patch for a second
>> >> >> >> >> > avcodec_find_best_pix_fmt_alt function that'll support more than 64
>> >> >> >> >> > formats as input to the function.
>> >> >> >> >>
>> >> >> >> >> You're welcome. And yes I agree we should replace the function with a
>> >> >> >> >> sane variant, for example:
>> >> >> >> >>
>> >> >> >> >> enum PixelFormat avcodec_find_best_pix_fmt2(int *pix_fmts, int pix_fmts_nb,
>> >> >> >> >> enum PixelFormat src_pix_fmt, ...);
>> >> >> >> >>
>> >> >> >> >> you pass a list of pixel formats (specifying the size, or
>> >> >> >> >> alternatively setting the last element to -1), no hardcoded limit on
>> >> >> >> >> the number of pixel formats.
>> >> >> >> >
>> >> >> >> > depending on how its used it might be simpler to have a function
>> >> >> >> > comparing 2 pixel formats
>> >> >> >> > int is_better_pix_fmt(enum PixelFormat *best, enum PixelFormat try,
>> >> >> >> > enum PixelFormat src_pix_fmt, ...);
>> >> >> >> >
>> >> >> >> > That would avoid having to build the array if it has to be build
>> >> >> >> >
>> >> >> >> That makes sense, however, the function (patch attached) should have
>> >> >> >> more than one destination
>> >> >> >> pixel format to choose from. The reason is that we already have a
>> >> >> >> avcodec_get_pix_fmt_loss() function
>> >> >> >> that could be used to find which pixel format is better as compared to another.
>> >> >> >> avcodec_find_best_pix_fmt() is typically used when you have a source
>> >> >> >> and multiple destination formats and you
>> >> >> >> like to find the best destination format, in that case comparing the
>> >> >> >> source to a single dest pixel fmt won't be helpful
>> >> >> >> directly because you want to compare multiple destination formats in
>> >> >> >> the "context" of the source format. I think the function
>> >> >> >> added in the patch solves that.
>> >> >> >>
>> >> >> >> See in the documentation of the function (in the patch) how this would
>> >> >> >> allow to find the best pixel format from a list of formats.
>> >> >> >>
>> >> >> >>
>> >> >> >> In addition, the function allows the user to select which type of loss
>> >> >> >> is acceptable to them (loss_ptr) and they aren't locked in to the
>> >> >> >> losses as enumerated
>> >> >> >> in the loss_mask_order array.
>> >> >> >>
>> >> >> >> Also, I didn't change the loss_mask_order array that enumerates losses
>> >> >> >> in increasing order. However, should that be edited? I'm not sure
>> >> >> >> why that order was selected, but I guess now is a good time as any to
>> >> >> >> look at that and possibly improve/increase that array? I don't know
>> >> >> >> much
>> >> >> >> about pix fmts so I don't know if that's already prefect.
>> >> >> >>
>> >> >> >> Thanks for the application of the previous patch,
>> >> >> >> Matt
>> >> >> >>
>> >> >> >> >
>> >> >> >> >>
>> >> >> >> >> >
>> >> >> >> >> > Thanks,
>> >> >> >> >> > Matt
>> >> >> >> >>
>> >> >> >> >> > From 076c8f936a46ea42cd4242eb4df2db265653d972 Mon Sep 17 00:00:00 2001
>> >> >> >> >> > From: Matthew Einhorn <moiein2000 at gmail.com>
>> >> >> >> >> > Date: Wed, 17 Aug 2011 01:58:33 -0400
>> >> >> >> >> > Subject: [PATCH] Fixes avcodec_find_best_pix_fmt() when there's more than 64
>> >> >> >> >> > pixel formats.
>> >> >> >> >> >
>> >> >> >> >> > This fixed the problem where if there's more than 64 pixel formats defined
>> >> >> >> >> > avcodec_find_best_pix_fmt() returns the wrong pixel format.
>> >> >> >> >> >
>> >> >> >> >> > Signed-off-by: Matthew Einhorn <moiein2000 at gmail.com>
>> >> >> >> >> > ---
>> >> >> >> >> > libavcodec/avcodec.h | 4 +++-
>> >> >> >> >> > libavcodec/imgconvert.c | 2 +-
>> >> >> >> >> > 2 files changed, 4 insertions(+), 2 deletions(-)
>> >> >> >> >> >
>> >> >> >> >> > diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
>> >> >> >> >> > index 4f0ed2d..f7d1520 100644
>> >> >> >> >> > --- a/libavcodec/avcodec.h
>> >> >> >> >> > +++ b/libavcodec/avcodec.h
>> >> >> >> >> > @@ -3496,9 +3496,11 @@ int avcodec_get_pix_fmt_loss(enum PixelFormat dst_pix_fmt, enum PixelFormat src_
>> >> >> >> >> > * The pixel formats from which it chooses one, are determined by the
>> >> >> >> >> > * pix_fmt_mask parameter.
>> >> >> >> >> > *
>> >> >> >> >> > + * Note, only the first 64 pixel formats will fit in pix_fmt_mask
>> >> >> >> >> > + *
>> >> >> >> >> > * @code
>> >> >> >> >> > * src_pix_fmt = PIX_FMT_YUV420P;
>> >> >> >> >> > - * pix_fmt_mask = (1 << PIX_FMT_YUV422P) || (1 << PIX_FMT_RGB24);
>> >> >> >> >> > + * pix_fmt_mask = (1 << PIX_FMT_YUV422P) | (1 << PIX_FMT_RGB24);
>> >> >> >> >> > * dst_pix_fmt = avcodec_find_best_pix_fmt(pix_fmt_mask, src_pix_fmt, alpha, &loss);
>> >> >> >> >> > * @endcode
>> >> >> >> >> > *
>> >> >> >> >> > diff --git a/libavcodec/imgconvert.c b/libavcodec/imgconvert.c
>> >> >> >> >> > index 9efed50..a4197cb 100644
>> >> >> >> >> > --- a/libavcodec/imgconvert.c
>> >> >> >> >> > +++ b/libavcodec/imgconvert.c
>> >> >> >> >> > @@ -439,7 +439,7 @@ static enum PixelFormat avcodec_find_best_pix_fmt1(int64_t pix_fmt_mask,
>> >> >> >> >> > /* find exact color match with smallest size */
>> >> >> >> >> > dst_pix_fmt = PIX_FMT_NONE;
>> >> >> >> >> > min_dist = 0x7fffffff;
>> >> >> >> >> > - for(i = 0;i < PIX_FMT_NB; i++) {
>> >> >> >> >> > + for(i = 0;i < FFMIN(PIX_FMT_NB, 64); i++) {
>> >> >> >> >> > if (pix_fmt_mask & (1ULL << i)) {
>> >> >> >> >> > loss = avcodec_get_pix_fmt_loss(i, src_pix_fmt, has_alpha) & loss_mask;
>> >> >> >> >> > if (loss == 0) {
>> >> >> >> >>
>> >> >> >> >> Looks fine to me, I'm going to apply soon if I read no comments (maybe
>> >> >> >> >> Michael?).
>> >> >> >> >
>> >> >> >> > LGTM
>> >> >> >> >
>> >> >> >> > [...]
>> >> >> >> > --
>> >> >> >> > Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>> >> >> >> >
>> >> >> >> > Observe your enemies, for they first find out your faults. -- Antisthenes
>> >> >> >> >
>> >> >> >> > -----BEGIN PGP SIGNATURE-----
>> >> >> >> > Version: GnuPG v1.4.10 (GNU/Linux)
>> >> >> >> >
>> >> >> >> > iEYEARECAAYFAk5LwucACgkQYR7HhwQLD6uSOwCfVwo3VbBwbFOUq76z0tCwkuEq
>> >> >> >> > QzIAn2kZ37gkkztp6KYVyBHXZ0Rx/m2w
>> >> >> >> > =/zSG
>> >> >> >> > -----END PGP SIGNATURE-----
>> >> >> >> >
>> >> >> >> > _______________________________________________
>> >> >> >> > ffmpeg-devel mailing list
>> >> >> >> > ffmpeg-devel at ffmpeg.org
>> >> >> >> > http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
>> >> >> >> >
>> >> >> >> >
>> >> >> >
>> >> >> >> avcodec.h | 34 ++++++++++++++++++++++++++++++++++
>> >> >> >> imgconvert.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
>> >> >> >> 2 files changed, 80 insertions(+)
>> >> >> >> a2185b7288f78de01eaf39b89f5de1d313643607 0001-Adds-a-new-pix-fmt-function-that-selects-the-best-de.patch
>> >> >> >> From a873e791be7802b110ac44e279b904d28e2e2fb4 Mon Sep 17 00:00:00 2001
>> >> >> >> From: Matthew Einhorn <moiein2000 at gmail.com>
>> >> >> >> Date: Wed, 17 Aug 2011 20:14:54 -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.
>> >> >> >>
>> >> >> >> Signed-off-by: Matthew Einhorn <moiein2000 at gmail.com>
>> >> >> >> ---
>> >> >> >> libavcodec/avcodec.h | 34 ++++++++++++++++++++++++++++++++++
>> >> >> >> libavcodec/imgconvert.c | 46 ++++++++++++++++++++++++++++++++++++++++++++++
>> >> >> >> 2 files changed, 80 insertions(+), 0 deletions(-)
>> >> >> >
>> >> >> > The old function should be replaced by the new and the old then
>> >> >> > implemented by using the new
>> >> >>
>> >> >> Should I implement new and re-implement old in one patch or in two patches?
>> >> >
>> >> > both in one patch
>> >> >
>> >> >
>> >> >>
>> >> >> Also, the old function makes use of an internal
>> >> >> avcodec_find_best_pix_fmt1() function which is used "only" by the old
>> >> >> function, can I remove that?
>> >> >
>> >> > yes but that should be a seperate patch
>> >> >
>> >> >
>> >> >>
>> >> >> Finally, the new function allows the input of PIX_FMT_NONE as a
>> >> >> destination format because it would simplify the use of it (if "one"
>> >> >> of the dest pix fmts can be -1) because you'd have to do less error
>> >> >> checking. However, to do that avcodec_get_pix_fmt_loss() also needs to
>> >> >> support the "dst_pix_fmt" parameter to be PIX_FMT_NONE (otherwise I
>> >> >> need to check for it in the new function). Would it be appropriate to
>> >> >> patch avcodec_get_pix_fmt_loss() to include a line of code at the
>> >> >> start where if the dest format is -1 it returns the maximum loss or
>> >> >> should it stay as undefined behavior (since arrays then get indexed by
>> >> >> -1)?
>> >> >
>> >> > yes, of course
>> >> >
>> >>
>> >> All three patches attached
>> >> Thanks,
>> >> Matt
>> >
>> >> avcodec.h | 34 ++++++++++++++++++++++++++++++++++
>> >> imgconvert.c | 47 ++++++++++++++++++++++++++++++++++++++++-------
>> >> 2 files changed, 74 insertions(+), 7 deletions(-)
>> >> a340d8792706166253efe4bbbcf411a00bf5a0f2 0001-Adds-a-new-pix-fmt-function-that-selects-the-best-de.patch
>> >> From 830379b3867e24bbe62fe2e305a3efb143ba2086 Mon Sep 17 00:00:00 2001
>> >> From: Matthew Einhorn <moiein2000 at gmail.com>
>> >> Date: Sun, 21 Aug 2011 12:42:11 -0400
>> >> Subject: [PATCH 1/3] 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.
>> >>
>> >> Signed-off-by: Matthew Einhorn <moiein2000 at gmail.com>
>> >> ---
>> >> libavcodec/avcodec.h | 34 ++++++++++++++++++++++++++++++++++
>> >> libavcodec/imgconvert.c | 47 ++++++++++++++++++++++++++++++++++++++++-------
>> >> 2 files changed, 74 insertions(+), 7 deletions(-)
>> >>
>> >> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
>> >> index 4f0ed2d..9d9c3c5 100644
>> >> --- a/libavcodec/avcodec.h
>> >> +++ b/libavcodec/avcodec.h
>> >> @@ -3508,8 +3508,42 @@ int avcodec_get_pix_fmt_loss(enum PixelFormat dst_pix_fmt, enum PixelFormat src_
>> >> * @param[out] loss_ptr Combination of flags informing you what kind of losses will occur.
>> >> * @return The best pixel format to convert to or -1 if none was found.
>> >> */
>> >> +
>> >> 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.
>> >> + *
>> >> + * @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 */
>> >> #define FF_ALPHA_SEMI_TRANSP 0x0002 /* image has some transparent pixels */
>> >> diff --git a/libavcodec/imgconvert.c b/libavcodec/imgconvert.c
>> >> index 9efed50..25cb2cb 100644
>> >> --- a/libavcodec/imgconvert.c
>> >> +++ b/libavcodec/imgconvert.c
>> >> @@ -455,10 +455,30 @@ static enum PixelFormat avcodec_find_best_pix_fmt1(int64_t pix_fmt_mask,
>> >> }
>> >>
>> >> enum PixelFormat avcodec_find_best_pix_fmt(int64_t pix_fmt_mask, enum PixelFormat src_pix_fmt,
>> >> - int has_alpha, int *loss_ptr)
>> >> + int has_alpha, int *loss_ptr)
>> >> {
>> >> enum PixelFormat dst_pix_fmt;
>> >> - int loss_mask, i;
>> >> + int i;
>> >> +
>> >
>> >> + if (loss_ptr) /* all losses count (for backward compatibility) */
>> >
>> > tabs are forbidden in ffmpeg git
>> >
>> >
>> >> + *loss_ptr= 0;
>> >
>> >> + i= -1;
>> >> + dst_pix_fmt= PIX_FMT_NONE; /* so first iteration doesn't have to be treated special */
>> >> + while (1){
>> >> + while(++i < FFMIN(PIX_FMT_NB, 64) && !(pix_fmt_mask & (1ULL << i)));
>> >> + if (i < FFMIN(PIX_FMT_NB, 64))
>> >> + dst_pix_fmt= avcodec_find_best_pix_fmt2(dst_pix_fmt, i, src_pix_fmt, has_alpha, loss_ptr);
>> >> + else
>> >> + break;
>> >> + }
>> >
>> > The following is simpler:
>> >
>> > for(i=0; i< FFMIN(PIX_FMT_NB, 64); i++){
>> > if(pix_fmt_mask & (1ULL << i))
>> > ...
>> > }
>> >
>> >
>> >
>> >> + return dst_pix_fmt;
>> >> +}
>> >> +
>> >> +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)
>> >> +{
>> >> + enum PixelFormat dst_pix_fmt;
>> >> + int loss1, loss2, i, loss_mask;
>> >> static const int loss_mask_order[] = {
>> >> ~0, /* no loss first */
>> >> ~FF_LOSS_ALPHA,
>> >> @@ -469,18 +489,31 @@ enum PixelFormat avcodec_find_best_pix_fmt(int64_t pix_fmt_mask, enum PixelForma
>> >> 0,
>> >> };
>> >>
>> >> + loss_mask= loss_ptr?~*loss_ptr:~0; /* use loss mask if provided */
>> >> + dst_pix_fmt = PIX_FMT_NONE;
>> >> /* try with successive loss */
>> >> i = 0;
>> >> for(;;) {
>> >> - loss_mask = loss_mask_order[i++];
>> >> - dst_pix_fmt = avcodec_find_best_pix_fmt1(pix_fmt_mask, src_pix_fmt,
>> >> - has_alpha, loss_mask);
>> >> + loss1 = avcodec_get_pix_fmt_loss(dst_pix_fmt1, src_pix_fmt, has_alpha) & loss_mask_order[i] & loss_mask;
>> >> + loss2 = avcodec_get_pix_fmt_loss(dst_pix_fmt2, src_pix_fmt, has_alpha) & loss_mask_order[i] & loss_mask;
>> >
>> > theres no need to call these 2 in a loop, their value doesnt change
>> >
>> >
>> >> +
>> >> + if (loss1 == 0 && loss2 == 0){ /* use format with smallest depth */
>> >> + dst_pix_fmt= avg_bits_per_pixel(dst_pix_fmt2)<avg_bits_per_pixel(dst_pix_fmt1)?dst_pix_fmt2:dst_pix_fmt1;
>> >> + } else if (loss1 == 0 || loss2 == 0) { /* use format with no loss */
>> >> + dst_pix_fmt= loss2?dst_pix_fmt1:dst_pix_fmt2;
>> >> + }
>> >> +
>> >> if (dst_pix_fmt >= 0)
>> >> goto found;
>> >> - if (loss_mask == 0)
>> >> + if (loss_mask_order[i++] == 0)
>> >> break;
>> >> }
>> >> - return PIX_FMT_NONE;
>> >
>> >> +
>> >> + /* none found only if one or both of dst_pix_fmts are -1, so return the other (valid) dst_pix_fmt that isn't -1 */
>> >> + if (dst_pix_fmt1 <PIX_FMT_NB && dst_pix_fmt1 > PIX_FMT_NONE)
>> >> + dst_pix_fmt= dst_pix_fmt1;
>> >> + if (dst_pix_fmt2 <PIX_FMT_NB && dst_pix_fmt2 > PIX_FMT_NONE)
>> >> + dst_pix_fmt= dst_pix_fmt2;
>> >
>> > this should not be necessary, invalid formats should already have the
>> > worst score, forcing the other to be selected
>> >
>>
>> Will fix the others, but for this last one, what if you have a pixel
>> format that has such bad losses that it would only get selected when
>> we AND it with the loss mask of 0 (last element in loss array). In
>> that case it would be equivalent to an invalid format in terms of
>> loss. Should I not worry about such a pixel format?
>
> the array could contain a entry before the 0 that contains all losses
> that might occur with actual pixel formats.
>
Updated and improved (patch1 from above) attached.
Thanks,
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: 6810 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20110821/bfbb8b35/attachment.obj>
More information about the ffmpeg-devel
mailing list