Fix JXS_video_descriptor schar field parsing in the MPEG-TS demuxer:
- Add 4:2:0 subsampling support (Ssub=2)
- Detect GBR/RGB pixel formats from colour_specification bits [11:8]
- Add comment clarifying bit depth comes from codestream, not descriptor
The schar field per ISO/IEC 21122-3 encodes colour_specification in
bits [11:8] (Cs: 0=YCbCr, 1=RGB/GBR) and subsampling in bits [3:0]
(Ssub: 0=4:2:2, 1=4:4:4, 2=4:2:0). The previous code only handled
Ssub 0 and 1, and did not check Cs bits for GBR detection.
---
libavformat/mpegts.c | 20 +++++++++++++++++---
1 file changed, 17 insertions(+), 3 deletions(-)
diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
index 4b326d309b..6b94ebd785 100644
--- a/libavformat/mpegts.c
+++ b/libavformat/mpegts.c
@@ -1901,11 +1901,25 @@ static int
parse_mpeg2_extension_descriptor(AVFormatContext *fc, AVStream *st, i
st->codecpar->framerate.den = framerate_den;
}
+ /* schar bits [11:8] = Cs (colour_specification), bits [3:0] =
Ssub (subsampling).
+ * Bit depth is not carried in schar; it comes from the codestream.
+ * Set a reasonable default format per subsampling; the parser will
+ * refine it once the first frame is parsed. */
switch (schar & 0xf) {
- case 0: st->codecpar->format = AV_PIX_FMT_YUV422P10LE; break;
- case 1: st->codecpar->format = AV_PIX_FMT_YUV444P10LE; break;
+ case 0: /* 4:2:2 */
+ st->codecpar->format = AV_PIX_FMT_YUV422P10LE;
+ break;
+ case 1: /* 4:4:4 */
+ if (((schar >> 8) & 0xf) == 1)
+ st->codecpar->format = AV_PIX_FMT_GBRP10LE;
+ else
+ st->codecpar->format = AV_PIX_FMT_YUV444P10LE;
+ break;
+ case 2: /* 4:2:0 */
+ st->codecpar->format = AV_PIX_FMT_YUV420P10LE;
+ break;
default:
- av_log(fc, AV_LOG_WARNING, "Unknown JPEG XS sampling format");
+ av_log(fc, AV_LOG_WARNING, "Unknown JPEG XS sampling format
%d\n", schar & 0xf);
break;
}
--
2.53.0
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