| Message ID | 20240108145336.380094-1-jeff@jeffreyknockel.com |
|---|---|
| State | New |
| Headers | show |
| Series | [FFmpeg-devel] avutil/pixfmt: fix AV_PIX_FMT_RGB8 description | expand |
| Context | Check | Description |
|---|---|---|
| yinshiyou/make_loongarch64 | success | Make finished |
| yinshiyou/make_fate_loongarch64 | success | Make fate finished |
| andriy/make_x86 | success | Make finished |
| andriy/make_fate_x86 | success | Make fate finished |
On date Monday 2024-01-08 09:53:37 -0500, Jeffrey Knockel wrote: > Previously the description was partially mistaken, explaining the format > as RGB 3:3:2, (msb)2R 3G 3B(lsb). While the RGB 3:3:2 part is correct, > the latter part should be: (msb)3R 3G 2B(lsb). The corresponding bit > masks are red: 0xE0, green: 0x1C, blue: 0x03. > > Signed-off-by: Jeffrey Knockel <jeff@jeffreyknockel.com> > --- > libavutil/pixfmt.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/libavutil/pixfmt.h b/libavutil/pixfmt.h > index 58f9ad28bd..9c87571f49 100644 > --- a/libavutil/pixfmt.h > +++ b/libavutil/pixfmt.h > @@ -83,7 +83,7 @@ enum AVPixelFormat { > AV_PIX_FMT_BGR8, ///< packed RGB 3:3:2, 8bpp, (msb)2B 3G 3R(lsb) > AV_PIX_FMT_BGR4, ///< packed RGB 1:2:1 bitstream, 4bpp, (msb)1B 2G 1R(lsb), a byte contains two pixels, the first pixel in the byte is the one composed by the 4 msb bits > AV_PIX_FMT_BGR4_BYTE, ///< packed RGB 1:2:1, 8bpp, (msb)1B 2G 1R(lsb) > - AV_PIX_FMT_RGB8, ///< packed RGB 3:3:2, 8bpp, (msb)2R 3G 3B(lsb) > + AV_PIX_FMT_RGB8, ///< packed RGB 3:3:2, 8bpp, (msb)3R 3G 2B(lsb) This is not consistent with pixdesc definition: [AV_PIX_FMT_RGB8] = { .name = "rgb8", .nb_components = 3, .log2_chroma_w = 0, .log2_chroma_h = 0, .comp = { { 0, 1, 0, 6, 2 }, /* R */ { 0, 1, 0, 3, 3 }, /* G */ { 0, 1, 0, 0, 3 }, /* B */ }, .flags = AV_PIX_FMT_FLAG_RGB, }, so either the documentation or the pixdesc description is wrong. Do you confirm "(msb)3R 3G 2B(lsb)" is the correct definition? In this case pixdesc should be fixed accordingly. Thanks.
On 1/14/24 6:32 AM, Stefano Sabatini wrote: > On date Monday 2024-01-08 09:53:37 -0500, Jeffrey Knockel wrote: >> Previously the description was partially mistaken, explaining the format >> as RGB 3:3:2, (msb)2R 3G 3B(lsb). While the RGB 3:3:2 part is correct, >> the latter part should be: (msb)3R 3G 2B(lsb). The corresponding bit >> masks are red: 0xE0, green: 0x1C, blue: 0x03. >> >> Signed-off-by: Jeffrey Knockel <jeff@jeffreyknockel.com> >> --- >> libavutil/pixfmt.h | 2 +- >> 1 file changed, 1 insertion(+), 1 deletion(-) >> >> diff --git a/libavutil/pixfmt.h b/libavutil/pixfmt.h >> index 58f9ad28bd..9c87571f49 100644 >> --- a/libavutil/pixfmt.h >> +++ b/libavutil/pixfmt.h >> @@ -83,7 +83,7 @@ enum AVPixelFormat { >> AV_PIX_FMT_BGR8, ///< packed RGB 3:3:2, 8bpp, (msb)2B 3G 3R(lsb) >> AV_PIX_FMT_BGR4, ///< packed RGB 1:2:1 bitstream, 4bpp, (msb)1B 2G 1R(lsb), a byte contains two pixels, the first pixel in the byte is the one composed by the 4 msb bits >> AV_PIX_FMT_BGR4_BYTE, ///< packed RGB 1:2:1, 8bpp, (msb)1B 2G 1R(lsb) > >> - AV_PIX_FMT_RGB8, ///< packed RGB 3:3:2, 8bpp, (msb)2R 3G 3B(lsb) >> + AV_PIX_FMT_RGB8, ///< packed RGB 3:3:2, 8bpp, (msb)3R 3G 2B(lsb) > > This is not consistent with pixdesc definition: > [AV_PIX_FMT_RGB8] = { > .name = "rgb8", > .nb_components = 3, > .log2_chroma_w = 0, > .log2_chroma_h = 0, > .comp = { > { 0, 1, 0, 6, 2 }, /* R */ > { 0, 1, 0, 3, 3 }, /* G */ > { 0, 1, 0, 0, 3 }, /* B */ > }, > .flags = AV_PIX_FMT_FLAG_RGB, > }, > > so either the documentation or the pixdesc description is wrong. > > Do you confirm "(msb)3R 3G 2B(lsb)" is the correct definition? Yes, I created three solid-colored RGBA raw samples filled with either #ff0000ff, #00ff00ff, or #0000ffff, and converted them using `ffmpeg ... -pix_fmt rgba ... -pix_fmt rgb8 ...` and inspected the output. I also tested with `ffmpeg ... -pix_fmt rgba ... -pix_fmt yuv420p ...` followed by `ffmpeg ... -pix_fmt yuv420p ... -pix_fmt rgb8 ...`. In these tests the outputs were consistent with "(msb)3R 3G 2B(lsb)". > In this case pixdesc should be fixed accordingly. Got it, will send an updated patch! Thanks, Jeff
diff --git a/libavutil/pixfmt.h b/libavutil/pixfmt.h index 58f9ad28bd..9c87571f49 100644 --- a/libavutil/pixfmt.h +++ b/libavutil/pixfmt.h @@ -83,7 +83,7 @@ enum AVPixelFormat { AV_PIX_FMT_BGR8, ///< packed RGB 3:3:2, 8bpp, (msb)2B 3G 3R(lsb) AV_PIX_FMT_BGR4, ///< packed RGB 1:2:1 bitstream, 4bpp, (msb)1B 2G 1R(lsb), a byte contains two pixels, the first pixel in the byte is the one composed by the 4 msb bits AV_PIX_FMT_BGR4_BYTE, ///< packed RGB 1:2:1, 8bpp, (msb)1B 2G 1R(lsb) - AV_PIX_FMT_RGB8, ///< packed RGB 3:3:2, 8bpp, (msb)2R 3G 3B(lsb) + AV_PIX_FMT_RGB8, ///< packed RGB 3:3:2, 8bpp, (msb)3R 3G 2B(lsb) AV_PIX_FMT_RGB4, ///< packed RGB 1:2:1 bitstream, 4bpp, (msb)1R 2G 1B(lsb), a byte contains two pixels, the first pixel in the byte is the one composed by the 4 msb bits AV_PIX_FMT_RGB4_BYTE, ///< packed RGB 1:2:1, 8bpp, (msb)1R 2G 1B(lsb) AV_PIX_FMT_NV12, ///< planar YUV 4:2:0, 12bpp, 1 plane for Y and 1 plane for the UV components, which are interleaved (first byte U and the following byte V)
Previously the description was partially mistaken, explaining the format as RGB 3:3:2, (msb)2R 3G 3B(lsb). While the RGB 3:3:2 part is correct, the latter part should be: (msb)3R 3G 2B(lsb). The corresponding bit masks are red: 0xE0, green: 0x1C, blue: 0x03. Signed-off-by: Jeffrey Knockel <jeff@jeffreyknockel.com> --- libavutil/pixfmt.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)