Hi
It seems 25 fps DV muxed in GXF is misdetected as 50 fps by lavf.
The attached patch fixes this issue by setting the duration of DV
packets to fields_per_frame.
Without this ffprobe reports packets as having duration=1, but all
dts:es are even (0, 2, 4, time_base=1/50) which confuses lavf.
I chose only to do this for DV since MPEG-2 seems to work fine, and I
can't find any other samples.
Sample: http://titan.codemill.se/~tomhar/samples/gxf_dv25_fps_misdetect.gxf
/Tomas
>From b4166c842605348319dd20c39cb90b4fc5b26901 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tomas=20H=C3=A4rdin?= <tomas.har...@codemill.se>
Date: Thu, 23 Jun 2011 15:59:33 +0200
Subject: [PATCH] gxf: Fix 25 fps DV material in GXF being misdetected as 50 fps
Set DV packet durations using fields_per_frame.
This requires turning gxf_stream_info into the demuxer's context for access to the value in gxf_packet().
Since MPEG-2 seems to work fine this done only for DV.
---
libavformat/gxf.c | 25 ++++++++++++++++---------
1 files changed, 16 insertions(+), 9 deletions(-)
diff --git a/libavformat/gxf.c b/libavformat/gxf.c
index e278b9b..145b4ad 100644
--- a/libavformat/gxf.c
+++ b/libavformat/gxf.c
@@ -264,7 +264,7 @@ static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
int map_len;
int len;
AVRational main_timebase = {0, 0};
- struct gxf_stream_info si;
+ struct gxf_stream_info *si = s->priv_data;
int i;
if (!parse_packet_header(pb, &pkt_type, &map_len) || pkt_type != PKT_MAP) {
av_log(s, AV_LOG_ERROR, "map packet not found\n");
@@ -282,7 +282,7 @@ static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
return 0;
}
map_len -= len;
- gxf_material_tags(pb, &len, &si);
+ gxf_material_tags(pb, &len, si);
avio_skip(pb, len);
map_len -= 2;
len = avio_rb16(pb); // length of track description
@@ -300,7 +300,7 @@ static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
track_id = avio_r8(pb);
track_len = avio_rb16(pb);
len -= track_len;
- gxf_track_tags(pb, &track_len, &si);
+ gxf_track_tags(pb, &track_len, si);
avio_skip(pb, track_len);
if (!(track_type & 0x80)) {
av_log(s, AV_LOG_ERROR, "invalid track type %x\n", track_type);
@@ -316,12 +316,12 @@ static int gxf_header(AVFormatContext *s, AVFormatParameters *ap) {
if (idx < 0) continue;
st = s->streams[idx];
if (!main_timebase.num || !main_timebase.den) {
- main_timebase.num = si.frames_per_second.den;
- main_timebase.den = si.frames_per_second.num * 2;
+ main_timebase.num = si->frames_per_second.den;
+ main_timebase.den = si->frames_per_second.num * 2;
}
- st->start_time = si.first_field;
- if (si.first_field != AV_NOPTS_VALUE && si.last_field != AV_NOPTS_VALUE)
- st->duration = si.last_field - si.first_field;
+ st->start_time = si->first_field;
+ if (si->first_field != AV_NOPTS_VALUE && si->last_field != AV_NOPTS_VALUE)
+ st->duration = si->last_field - si->first_field;
}
if (len < 0)
av_log(s, AV_LOG_ERROR, "invalid track description length specified\n");
@@ -422,6 +422,8 @@ static int gxf_packet(AVFormatContext *s, AVPacket *pkt) {
AVIOContext *pb = s->pb;
GXFPktType pkt_type;
int pkt_len;
+ struct gxf_stream_info *si = s->priv_data;
+
while (!url_feof(pb)) {
AVStream *st;
int track_type, track_id, ret;
@@ -473,6 +475,11 @@ static int gxf_packet(AVFormatContext *s, AVPacket *pkt) {
avio_skip(pb, skip);
pkt->stream_index = stream_index;
pkt->dts = field_nr;
+
+ //set duration manually for DV or else lavf misdetects the frame rate
+ if (st->codec->codec_id == CODEC_ID_DVVIDEO)
+ pkt->duration = si->fields_per_frame;
+
return ret;
}
return AVERROR(EIO);
@@ -518,7 +525,7 @@ static int64_t gxf_read_timestamp(AVFormatContext *s, int stream_index,
AVInputFormat ff_gxf_demuxer = {
"gxf",
NULL_IF_CONFIG_SMALL("GXF format"),
- 0,
+ sizeof(struct gxf_stream_info),
gxf_probe,
gxf_header,
gxf_packet,
--
1.7.1
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