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new 4c6d67fe0f avformat/mov, movenc: add the dav1 sample entry for AV1
Dolby Vision
4c6d67fe0f is described below
commit 4c6d67fe0fc6b9a0bd9b2032f3e948d481206d9c
Author: Vincent Herbst <[email protected]>
AuthorDate: Fri Sep 18 08:50:03 2026 +0200
Commit: James Almer <[email protected]>
CommitDate: Fri Sep 18 23:21:38 2026 +0000
avformat/mov, movenc: add the dav1 sample entry for AV1 Dolby Vision
MP4RA registers 'dav1' as a variant of 'av01' that signals Dolby Vision.
Dolby Vision Profile 10.0 uses it: the AV1 counterpart of HEVC Profile 5,
an IPT-PQ-c2 signal with no compatible base layer, so 'av01' is not an
alternative there. The cross-compatible profiles (10.1, 10.2, 10.4) keep
an 'av01' entry and are unaffected.
Two tables are involved and each covers one direction.
Without the isom_tags.c entry the sample entry is not recognized, so a
file a conforming muxer writes cannot be read. GPAC writes it, and the
whole file can be built from public tools:
$ ffmpeg -f lavfi -i testsrc=size=640x360:rate=24:duration=2 \
-c:v libsvtav1 -pix_fmt yuv420p10le -color_primaries bt2020 \
-color_trc smpte2084 -colorspace bt2020nc -f obu av1.obu
$ MP4Box -add "av1.obu:dvp=f10:stype=dav1" -new dv100.mp4
$ ffprobe dv100.mp4
Video: none (dav1 / 0x31766164), none, 640x360
Could not find codec parameters for stream 0: unknown codec
Without the codec_mp4_tags entry in movenc.c, validate_codec_tag() finds
no match for a requested tag and mov_init() bails:
$ ffmpeg -i av1.mp4 -c copy -tag:v dav1 out.mp4
Tag dav1 incompatible with output codec id '225' (av01)
Could not write header (incorrect codec parameters ?)
'dvh1' sits in that second table for the HEVC side already, which is what
makes the Profile 5 remux work today.
With both entries the GPAC file probes as av1, and a remux with
-tag:v dav1 writes a 'dav1' sample entry whose av1C parses back to
yuv420p10le. The 'av01' path is unchanged.
The isom_tags.c half was proposed in 2023 as
[email protected] and not applied.
---
libavformat/isom_tags.c | 1 +
libavformat/movenc.c | 1 +
2 files changed, 2 insertions(+)
diff --git a/libavformat/isom_tags.c b/libavformat/isom_tags.c
index c0c239d393..06166c0fa8 100644
--- a/libavformat/isom_tags.c
+++ b/libavformat/isom_tags.c
@@ -155,6 +155,7 @@ const AVCodecTag ff_codec_movvideo_tags[] = {
{ AV_CODEC_ID_VP8, MKTAG('v', 'p', '0', '8') }, /* VP8 */
{ AV_CODEC_ID_VP9, MKTAG('v', 'p', '0', '9') }, /* VP9 */
{ AV_CODEC_ID_AV1, MKTAG('a', 'v', '0', '1') }, /* AV1 */
+ { AV_CODEC_ID_AV1, MKTAG('d', 'a', 'v', '1') }, /* AV1-related Dolby
Vision */
{ AV_CODEC_ID_MPEG1VIDEO, MKTAG('m', '1', 'v', ' ') },
{ AV_CODEC_ID_MPEG1VIDEO, MKTAG('m', '1', 'v', '1') }, /* Apple MPEG-1
Camcorder */
diff --git a/libavformat/movenc.c b/libavformat/movenc.c
index ecc6544bad..b43ad655b4 100644
--- a/libavformat/movenc.c
+++ b/libavformat/movenc.c
@@ -9359,6 +9359,7 @@ static const AVCodecTag codec_mp4_tags[] = {
{ AV_CODEC_ID_TSCC2, MKTAG('m', 'p', '4', 'v') },
{ AV_CODEC_ID_VP9, MKTAG('v', 'p', '0', '9') },
{ AV_CODEC_ID_AV1, MKTAG('a', 'v', '0', '1') },
+ { AV_CODEC_ID_AV1, MKTAG('d', 'a', 'v', '1') },
{ AV_CODEC_ID_AAC, MKTAG('m', 'p', '4', 'a') },
{ AV_CODEC_ID_APPLE_APAC, MKTAG('a', 'p', 'a', 'c') },
{ AV_CODEC_ID_ALAC, MKTAG('a', 'l', 'a', 'c') },
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