[FFmpeg-devel] [PATCH] lavu/pixdesc: favour formats where bit depth exactly matches
Philip Langdale
philipl at overt.org
Fri Sep 9 06:46:11 EEST 2022
Since introducing the various packed formats used by VAAPI (and p012),
we've noticed that there's actually a gap in how
av_find_best_pix_fmt_of_2 works. It doesn't actually assign any value
to having the same bit depth as the source format, when comparing
against formats with a higher bit depth. This usually doesn't matter,
because av_get_padded_bits_per_pixel() will account for it.
However, as many of these formats use padding internally, we find that
av_get_padded_bits_per_pixel() actually returns the same value for the
10 bit, 12, bit, 16 bit flavours, etc. In these tied situations, we end
up just picking the first of the two provided formats, even if the
second one should be preferred because it matches the actual bit depth.
This bug already existed if you tried to compare yuv420p10 against p016
and p010, for example, but it simply hadn't come up before so we never
noticed.
But now, we actually got a situation in the VAAPI VP9 decoder where it
offers both p010 and p012 because Profile 3 could be either depth and
ends up picking p012 for 10 bit content due to the ordering of the
testing.
In addition, in the process of testing the fix, I realised we have the
same gap when it comes to chroma subsampling - we do not favour a
format that has exactly the same subsampling vs one with less
subsampling when all else is equal.
To fix this, I'm introducing a small score penalty if the bit depth or
subsampling doesn't exactly match the source format. This will break
the tie in favour of the format with the exact match, but not offset
any of the other scoring penalties we already have.
I have added a set of tests around these formats which will fail
without this fix.
Signed-off-by: Philip Langdale <philipl at overt.org>
---
libavutil/pixdesc.c | 16 +++++-
libavutil/tests/pixfmt_best.c | 93 ++++++++++++++++++++++++++++-------
tests/ref/fate/pixfmt_best | 2 +-
3 files changed, 89 insertions(+), 22 deletions(-)
diff --git a/libavutil/pixdesc.c b/libavutil/pixdesc.c
index d7c6ebfdc4..412e257a30 100644
--- a/libavutil/pixdesc.c
+++ b/libavutil/pixdesc.c
@@ -3004,6 +3004,11 @@ static int get_pix_fmt_score(enum AVPixelFormat dst_pix_fmt,
if ((ret = get_pix_fmt_depth(&dst_min_depth, &dst_max_depth, dst_pix_fmt)) < 0)
return -3;
+ // Favour formats where bit depth exactly matches. If all other scoring is
+ // equal, we'd rather use a lower bit depth that matches the source.
+ if (src_min_depth != dst_min_depth || src_max_depth != dst_max_depth)
+ score -= 64;
+
src_color = get_color_type(src_desc);
dst_color = get_color_type(dst_desc);
if (dst_pix_fmt == AV_PIX_FMT_PAL8)
@@ -3020,14 +3025,21 @@ static int get_pix_fmt_score(enum AVPixelFormat dst_pix_fmt,
}
if (consider & FF_LOSS_RESOLUTION) {
+ // Apply a large penalty if there's a loss of resolution, but also apply
+ // a small penalty of the dst resolution is higher so that we favour
+ // exactly matching formats.
if (dst_desc->log2_chroma_w > src_desc->log2_chroma_w) {
loss |= FF_LOSS_RESOLUTION;
score -= 256 << dst_desc->log2_chroma_w;
- }
+ } else if (dst_desc->log2_chroma_w < src_desc->log2_chroma_w)
+ score -= 32;
+
if (dst_desc->log2_chroma_h > src_desc->log2_chroma_h) {
loss |= FF_LOSS_RESOLUTION;
score -= 256 << dst_desc->log2_chroma_h;
- }
+ } else if (dst_desc->log2_chroma_h < src_desc->log2_chroma_h)
+ score -= 32;
+
// don't favor 422 over 420 if downsampling is needed, because 420 has much better support on the decoder side
if (dst_desc->log2_chroma_w == 1 && src_desc->log2_chroma_w == 0 &&
dst_desc->log2_chroma_h == 1 && src_desc->log2_chroma_h == 0 ) {
diff --git a/libavutil/tests/pixfmt_best.c b/libavutil/tests/pixfmt_best.c
index 0542af494f..b5d4d04976 100644
--- a/libavutil/tests/pixfmt_best.c
+++ b/libavutil/tests/pixfmt_best.c
@@ -39,32 +39,59 @@ static const enum AVPixelFormat pixfmt_list[] = {
AV_PIX_FMT_VAAPI,
};
-static enum AVPixelFormat find_best(enum AVPixelFormat pixfmt)
+static const enum AVPixelFormat semiplanar_list[] = {
+ AV_PIX_FMT_P016,
+ AV_PIX_FMT_P012,
+ AV_PIX_FMT_P010,
+ AV_PIX_FMT_NV12,
+};
+
+static const enum AVPixelFormat packed_list[] = {
+ AV_PIX_FMT_XV36,
+ AV_PIX_FMT_XV30,
+ AV_PIX_FMT_VUYX,
+ AV_PIX_FMT_Y212,
+ AV_PIX_FMT_Y210,
+ AV_PIX_FMT_YUYV422,
+};
+
+typedef enum AVPixelFormat (*find_best_t)(enum AVPixelFormat pixfmt);
+
+#define find_best_wrapper(name, list) \
+static enum AVPixelFormat find_best_ ## name (enum AVPixelFormat pixfmt) \
+{ \
+ enum AVPixelFormat best = AV_PIX_FMT_NONE; \
+ int i; \
+ for (i = 0; i < FF_ARRAY_ELEMS(list); i++) \
+ best = av_find_best_pix_fmt_of_2(best, list[i], \
+ pixfmt, 0, NULL); \
+ return best; \
+}
+
+find_best_wrapper(base, pixfmt_list)
+find_best_wrapper(seminplanar, semiplanar_list)
+find_best_wrapper(packed, packed_list)
+
+static void test(enum AVPixelFormat input, enum AVPixelFormat expected,
+ int *pass, int *fail, find_best_t find_best_fn)
{
- enum AVPixelFormat best = AV_PIX_FMT_NONE;
- int i;
- for (i = 0; i < FF_ARRAY_ELEMS(pixfmt_list); i++)
- best = av_find_best_pix_fmt_of_2(best, pixfmt_list[i],
- pixfmt, 0, NULL);
- return best;
+ enum AVPixelFormat output = find_best_fn(input);
+ if (output != expected) {
+ printf("Matching %s: got %s, expected %s\n",
+ av_get_pix_fmt_name(input),
+ av_get_pix_fmt_name(output),
+ av_get_pix_fmt_name(expected));
+ ++(*fail);
+ } else
+ ++(*pass);
}
int main(void)
{
- enum AVPixelFormat output;
int i, pass = 0, fail = 0;
-#define TEST(input, expected) do { \
- output = find_best(input); \
- if (output != expected) { \
- printf("Matching %s: got %s, expected %s\n", \
- av_get_pix_fmt_name(input), \
- av_get_pix_fmt_name(output), \
- av_get_pix_fmt_name(expected)); \
- ++fail; \
- } else \
- ++pass; \
- } while (0)
+#define TEST(input, expected) \
+ test(input, expected, &pass, &fail, find_best_base);
// Same formats.
for (i = 0; i < FF_ARRAY_ELEMS(pixfmt_list); i++)
@@ -137,6 +164,34 @@ int main(void)
// Opaque formats are least unlike each other.
TEST(AV_PIX_FMT_DXVA2_VLD, AV_PIX_FMT_VDPAU);
+#define TEST_SEMIPLANAR(input, expected) \
+ test(input, expected, &pass, &fail, find_best_seminplanar);
+
+ // Same formats.
+ for (i = 0; i < FF_ARRAY_ELEMS(semiplanar_list); i++)
+ TEST_SEMIPLANAR(semiplanar_list[i], semiplanar_list[i]);
+
+ // Formats containing the same data in different layouts.
+ TEST_SEMIPLANAR(AV_PIX_FMT_YUV420P, AV_PIX_FMT_NV12);
+ TEST_SEMIPLANAR(AV_PIX_FMT_YUV420P10, AV_PIX_FMT_P010);
+ TEST_SEMIPLANAR(AV_PIX_FMT_YUV420P12, AV_PIX_FMT_P012);
+ TEST_SEMIPLANAR(AV_PIX_FMT_YUV420P16, AV_PIX_FMT_P016);
+
+#define TEST_PACKED(input, expected) \
+ test(input, expected, &pass, &fail, find_best_packed);
+
+ // Same formats.
+ for (i = 0; i < FF_ARRAY_ELEMS(packed_list); i++)
+ TEST_PACKED(packed_list[i], packed_list[i]);
+
+ // Formats containing the same data in different layouts.
+ TEST_PACKED(AV_PIX_FMT_YUV444P, AV_PIX_FMT_VUYX);
+ TEST_PACKED(AV_PIX_FMT_YUV444P10, AV_PIX_FMT_XV30);
+ TEST_PACKED(AV_PIX_FMT_YUV444P12, AV_PIX_FMT_XV36);
+ TEST_PACKED(AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUYV422);
+ TEST_PACKED(AV_PIX_FMT_YUV422P10, AV_PIX_FMT_Y210);
+ TEST_PACKED(AV_PIX_FMT_YUV422P12, AV_PIX_FMT_Y212);
+
printf("%d tests passed, %d tests failed.\n", pass, fail);
return !!fail;
}
diff --git a/tests/ref/fate/pixfmt_best b/tests/ref/fate/pixfmt_best
index 783c5fe640..63911e7198 100644
--- a/tests/ref/fate/pixfmt_best
+++ b/tests/ref/fate/pixfmt_best
@@ -1 +1 @@
-75 tests passed, 0 tests failed.
+95 tests passed, 0 tests failed.
--
2.34.1
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