[FFmpeg-devel] [PATCH] Fixes avcodec_find_best_pix_fmt() with more than 64 pix fmts defined
Michael Niedermayer
michaelni at gmx.at
Sun Aug 21 20:56:49 CEST 2011
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.
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Let us carefully observe those good qualities wherein our enemies excel us
and endeavor to excel them, by avoiding what is faulty, and imitating what
is excellent in them. -- Plutarch
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