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Fix: VSE search in mpegts files would fail 

ffmpeg_generic_seek_workaround did work properly and our start pts
calculation was wrong.

Reviewed By: Richard Antalik

Differential Revision: http://developer.blender.org/D11562
This commit is contained in:
Sebastian Parborg 2021-06-10 02:38:28 +02:00 committed by Jeroen Bakker
parent 7616f4ae57
commit 444a8cbc2f
Notes: blender-bot 2023-02-14 05:41:57 +01:00 
Referenced by issue #88449, Blender LTS: Maintenance Task 2.93
2 changed files with 57 additions and 44 deletions
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20
intern/ffmpeg/ffmpeg_compat.h
View File

@ -92,26 +92,6 @@ void my_guess_pkt_duration(AVFormatContext *s, AVStream *st, AVPacket *pkt)
}
#endif
FFMPEG_INLINE
void my_update_cur_dts(AVFormatContext *s, AVStream *ref_st, int64_t timestamp)
{
int i;
for (i = 0; i < s->nb_streams; i++) {
AVStream *st = s->streams[i];
st->cur_dts = av_rescale(timestamp,
st->time_base.den * (int64_t)ref_st->time_base.num,
st->time_base.num * (int64_t)ref_st->time_base.den);
}
}
FFMPEG_INLINE
void av_update_cur_dts(AVFormatContext *s, AVStream *ref_st, int64_t timestamp)
{
my_update_cur_dts(s, ref_st, timestamp);
}
FFMPEG_INLINE
int64_t timestamp_from_pts_or_dts(int64_t pts, int64_t dts)
{

81
source/blender/imbuf/intern/anim_movie.c
View File

@ -1048,25 +1048,31 @@ static int64_t ffmpeg_get_seek_pos(struct anim *anim, int position)
return pos;
}
/* This gives us an estimate of which pts our requested frame will have.
* Note that this might be off a bit in certain video files, but it should still be close enough.
*/
static int64_t ffmpeg_get_pts_to_search(struct anim *anim,
struct anim_index *tc_index,
int position)
{
int64_t pts_to_search;
int64_t st_time = anim->pFormatCtx->start_time;
AVStream *v_st = anim->pFormatCtx->streams[anim->videoStream];
double frame_rate = av_q2d(av_guess_frame_rate(anim->pFormatCtx, v_st, NULL));
double pts_time_base = av_q2d(v_st->time_base);
if (tc_index) {
int new_frame_index = IMB_indexer_get_frame_index(tc_index, position);
pts_to_search = IMB_indexer_get_pts(tc_index, new_frame_index);
}
else {
pts_to_search = (long long)floor(((double)position) / pts_time_base / frame_rate + 0.5);
int64_t st_time = anim->pFormatCtx->start_time;
AVStream *v_st = anim->pFormatCtx->streams[anim->videoStream];
AVRational frame_rate = av_guess_frame_rate(anim->pFormatCtx, v_st, NULL);
AVRational time_base = v_st->time_base;
if (st_time != AV_NOPTS_VALUE) {
pts_to_search += st_time / pts_time_base / AV_TIME_BASE;
int64_t steps_per_frame = (frame_rate.den * time_base.den) / (frame_rate.num * time_base.num);
pts_to_search = position * steps_per_frame;
if (st_time != AV_NOPTS_VALUE && st_time != 0) {
int64_t start_frame = (double)st_time / AV_TIME_BASE * av_q2d(frame_rate);
pts_to_search += start_frame * steps_per_frame;
}
}
return pts_to_search;
@ -1100,6 +1106,7 @@ static void ffmpeg_decode_video_frame_scan(struct anim *anim, int64_t pts_to_sea
(int64_t)pts_to_search);
int64_t start_gop_frame = anim->cur_key_frame_pts;
bool scan_fuzzy = false;
while (anim->cur_pts < pts_to_search) {
av_log(anim->pFormatCtx,
@ -1114,6 +1121,14 @@ static void ffmpeg_decode_video_frame_scan(struct anim *anim, int64_t pts_to_sea
if (start_gop_frame != anim->cur_key_frame_pts) {
break;
}
if (anim->cur_pts < pts_to_search &&
anim->cur_pts + anim->pFrame->pkt_duration > pts_to_search) {
/* Our estimate of the pts was a bit off, but we have the frame we want. */
av_log(anim->pFormatCtx, AV_LOG_DEBUG, "SCAN fuzzy frame match\n");
scan_fuzzy = true;
break;
}
}
if (start_gop_frame != anim->cur_key_frame_pts) {
@ -1126,7 +1141,8 @@ static void ffmpeg_decode_video_frame_scan(struct anim *anim, int64_t pts_to_sea
(int64_t)anim->cur_pts,
(int64_t)pts_to_search);
}
if (anim->cur_pts == pts_to_search) {
if (scan_fuzzy || anim->cur_pts == pts_to_search) {
av_log(anim->pFormatCtx, AV_LOG_DEBUG, "SCAN HAPPY: we found our PTS!\n");
}
else {
@ -1139,17 +1155,19 @@ static void ffmpeg_decode_video_frame_scan(struct anim *anim, int64_t pts_to_sea
* necessary I-frame is not honored. It is not even guaranteed that I-frame, that must be
* decoded will be read. See https://trac.ffmpeg.org/ticket/1607 and
* https://developer.blender.org/T86944. */
static int ffmpeg_generic_seek_workaround(struct anim *anim, int64_t *requested_pos)
static int ffmpeg_generic_seek_workaround(struct anim *anim,
int64_t *requested_pos,
int64_t pts_to_search)
{
AVStream *v_st = anim->pFormatCtx->streams[anim->videoStream];
double frame_rate = av_q2d(av_guess_frame_rate(anim->pFormatCtx, v_st, NULL));
int64_t current_pos = *requested_pos;
int64_t offset = 0;
/* This time offset maximum limit is arbitrary. If some files fails to decode it may be
* increased. Seek performance will be negatively affected. Small initial offset is
* necessary because encoder can re-arrange frames as it needs but within it's delay, which
* is usually small. */
for (int offset = 5; offset < 25; offset++) {
int64_t cur_pts, prev_pts = -1;
/* Step backward frame by frame until we find the key frame we are looking for. */
while (current_pos != 0) {
current_pos = *requested_pos - ((int64_t)(offset)*AV_TIME_BASE / frame_rate);
current_pos = max_ii(current_pos, 0);
@ -1161,18 +1179,34 @@ static int ffmpeg_generic_seek_workaround(struct anim *anim, int64_t *requested_
/* Read first video stream packet. */
AVPacket *read_packet = av_packet_alloc();
while (av_read_frame(anim->pFormatCtx, read_packet) >= 0) {
if (anim->cur_packet->stream_index == anim->videoStream) {
if (read_packet->stream_index == anim->videoStream) {
break;
}
av_packet_unref(read_packet);
}
/* If this packet contains I-frame, exit loop. This should be the frame that we need. */
/* If this packet contains an I-frame, this could be the frame that we need. */
bool is_key_frame = read_packet->flags & AV_PKT_FLAG_KEY;
/* We need to check the packet timestamp as the key frame could be for a GOP forward in the the
* video stream. So if it has a larger timestamp than the frame we want, ignore it.
*/
cur_pts = timestamp_from_pts_or_dts(read_packet->pts, read_packet->dts);
av_packet_free(&read_packet);
if (is_key_frame) {
break;
if (cur_pts <= pts_to_search) {
/* We found the I-frame we were looking for! */
break;
}
if (cur_pts == prev_pts) {
/* We got the same key frame packet twice.
* This probably means that we have hit the beginning of the stream. */
break;
}
}
prev_pts = cur_pts;
offset++;
}
*requested_pos = current_pos;
@ -1182,10 +1216,11 @@ static int ffmpeg_generic_seek_workaround(struct anim *anim, int64_t *requested_
}
/* Seek to last necessary key frame. */
static int ffmpeg_seek_to_key_frame(struct anim *anim, int position, struct anim_index *tc_index)
static int ffmpeg_seek_to_key_frame(struct anim *anim,
int position,
struct anim_index *tc_index,
int64_t pts_to_search)
{
AVStream *v_st = anim->pFormatCtx->streams[anim->videoStream];
int64_t pos;
int ret;
@ -1215,7 +1250,6 @@ static int ffmpeg_seek_to_key_frame(struct anim *anim, int position, struct anim
av_log(anim->pFormatCtx, AV_LOG_DEBUG, "... using BYTE pos\n");
ret = av_seek_frame(anim->pFormatCtx, -1, pos, AVSEEK_FLAG_BYTE);
av_update_cur_dts(anim->pFormatCtx, v_st, dts);
}
else {
av_log(anim->pFormatCtx, AV_LOG_DEBUG, "... using PTS pos\n");
@ -1235,7 +1269,7 @@ static int ffmpeg_seek_to_key_frame(struct anim *anim, int position, struct anim
ret = av_seek_frame(anim->pFormatCtx, -1, pos, AVSEEK_FLAG_BACKWARD);
}
else {
ret = ffmpeg_generic_seek_workaround(anim, &pos);
ret = ffmpeg_generic_seek_workaround(anim, &pos, pts_to_search);
av_log(anim->pFormatCtx, AV_LOG_DEBUG, "Adjusted final seek pos = %" PRId64 "\n", pos);
}
@ -1277,7 +1311,6 @@ static int ffmpeg_seek_to_key_frame(struct anim *anim, int position, struct anim
}
if (ret < 0) {
int64_t pts_to_search = ffmpeg_get_pts_to_search(anim, tc_index, position);
av_log(anim->pFormatCtx,
AV_LOG_ERROR,
"FETCH: "
@ -1340,7 +1373,7 @@ static ImBuf *ffmpeg_fetchibuf(struct anim *anim, int position, IMB_Timecode_Typ
av_log(anim->pFormatCtx, AV_LOG_DEBUG, "FETCH: no seek necessary, just continue...\n");
ffmpeg_decode_video_frame(anim);
}
else if (ffmpeg_seek_to_key_frame(anim, position, tc_index) >= 0) {
else if (ffmpeg_seek_to_key_frame(anim, position, tc_index, pts_to_search) >= 0) {
ffmpeg_decode_video_frame_scan(anim, pts_to_search);
}