On 10/1/2019 2:56 PM, Calvin Walton wrote: > The ffmpeg code read and wrote a 64bit duration field (in timebase units) in > the ivf > header, where the libvpx and chromium code instead use a 32bit frame count > field, and > then 32bits of unused (reserved?) space. > > Switch ffmpeg to match the behaviour of libvpx & chromium. > > Note that libvpx writes 0 to the frame count field when initially writing the > header > then seeks back and overwrites it with the real frame count. ffmpeg used to > write > 0xFFFFFFFF - I've changed the behaviour to match libvpx. > > References: > https://github.com/webmproject/libvpx/blob/v1.8.1/ivfenc.c#L16 > Which is called from: > https://github.com/webmproject/libvpx/blob/v1.8.1/vpxenc.c#L1191 (initial > header) > https://github.com/webmproject/libvpx/blob/v1.8.1/vpxenc.c#L1209 (rewrite > with frame count) > And the chromium parser: > https://chromium.googlesource.com/chromium/src/media/+/1681b9abff73fe0e3d0932aefdab4f039a284d1a/filters/ivf_parser.h > --- > libavformat/ivfdec.c | 3 ++- > libavformat/ivfenc.c | 11 ++++------- > 2 files changed, 6 insertions(+), 8 deletions(-) > > diff --git a/libavformat/ivfdec.c b/libavformat/ivfdec.c > index 40ae464b76..2eaa5164ff 100644 > --- a/libavformat/ivfdec.c > +++ b/libavformat/ivfdec.c > @@ -53,7 +53,8 @@ static int read_header(AVFormatContext *s) > st->codecpar->height = avio_rl16(s->pb); > time_base.den = avio_rl32(s->pb); > time_base.num = avio_rl32(s->pb); > - st->duration = avio_rl64(s->pb); > + st->nb_frames = avio_rl32(s->pb);
The demuxer will report N/A as duration after this. > + avio_skip(s->pb, 4); // 32 bits unused > > st->need_parsing = AVSTREAM_PARSE_HEADERS; > > diff --git a/libavformat/ivfenc.c b/libavformat/ivfenc.c > index adf72117e9..85ca6045ba 100644 > --- a/libavformat/ivfenc.c > +++ b/libavformat/ivfenc.c > @@ -22,8 +22,7 @@ > #include "libavutil/intreadwrite.h" > > typedef struct IVFEncContext { > - unsigned frame_cnt; > - uint64_t last_pts, sum_delta_pts; > + uint32_t frame_cnt; > } IVFEncContext; > > static int ivf_write_header(AVFormatContext *s) > @@ -53,7 +52,8 @@ static int ivf_write_header(AVFormatContext *s) > avio_wl16(pb, par->height); > avio_wl32(pb, s->streams[0]->time_base.den); > avio_wl32(pb, s->streams[0]->time_base.num); > - avio_wl64(pb, 0xFFFFFFFFFFFFFFFFULL); > + avio_wl32(pb, 0); // frame count > + avio_wl32(pb, 0); // unused > > return 0; > } > @@ -66,10 +66,7 @@ static int ivf_write_packet(AVFormatContext *s, AVPacket > *pkt) > avio_wl32(pb, pkt->size); > avio_wl64(pb, pkt->pts); > avio_write(pb, pkt->data, pkt->size); > - if (ctx->frame_cnt) > - ctx->sum_delta_pts += pkt->pts - ctx->last_pts; > ctx->frame_cnt++; > - ctx->last_pts = pkt->pts; > > return 0; > } > @@ -83,7 +80,7 @@ static int ivf_write_trailer(AVFormatContext *s) > size_t end = avio_tell(pb); > > avio_seek(pb, 24, SEEK_SET); > - avio_wl64(pb, ctx->frame_cnt * ctx->sum_delta_pts / (ctx->frame_cnt > - 1)); > + avio_wl32(pb, ctx->frame_cnt); > avio_seek(pb, end, SEEK_SET); > } Similarly, old versions of the ivf demuxer will read bogus duration values after this change. _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".