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ismindex: handle discontinuous streams better

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Read the fragment duration from the trun sample data, rather than
assuming that there are no gaps.

Signed-off-by: Martin Storsjö <martin@martin.st>
This commit is contained in:
Mika Raento
2014-10-08 09:39:26 +03:00
committed by Martin Storsjö
parent 1a02e78653
commit 2bc220958c
1 changed files with 86 additions and 10 deletions
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96
tools/ismindex.c
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@@ -48,6 +48,7 @@
#include <string.h>
#include "libavformat/avformat.h"
#include "libavformat/isom.h"
#include "libavformat/os_support.h"
#include "libavutil/intreadwrite.h"
#include "libavutil/mathematics.h"
@@ -224,6 +225,79 @@ fail:
return ret;
}
static int64_t read_trun_duration(AVIOContext *in, int64_t end)
{
int64_t ret = 0;
int64_t pos;
int flags, i;
int entries;
avio_r8(in); /* version */
flags = avio_rb24(in);
if (!(flags & MOV_TRUN_SAMPLE_DURATION)) {
fprintf(stderr, "No sample duration in trun flags\n");
return -1;
}
entries = avio_rb32(in);
if (flags & MOV_TRUN_DATA_OFFSET) avio_rb32(in);
if (flags & MOV_TRUN_FIRST_SAMPLE_FLAGS) avio_rb32(in);
pos = avio_tell(in);
for (i = 0; i < entries && pos < end; i++) {
int sample_duration = 0;
if (flags & MOV_TRUN_SAMPLE_DURATION) sample_duration = avio_rb32(in);
if (flags & MOV_TRUN_SAMPLE_SIZE) avio_rb32(in);
if (flags & MOV_TRUN_SAMPLE_FLAGS) avio_rb32(in);
if (flags & MOV_TRUN_SAMPLE_CTS) avio_rb32(in);
if (sample_duration < 0) {
fprintf(stderr, "Negative sample duration %d\n", sample_duration);
return -1;
}
ret += sample_duration;
pos = avio_tell(in);
}
return ret;
}
static int64_t read_moof_duration(AVIOContext *in, int64_t offset)
{
int64_t ret = -1;
int32_t moof_size, size, tag;
int64_t pos = 0;
avio_seek(in, offset, SEEK_SET);
moof_size = avio_rb32(in);
tag = avio_rb32(in);
if (expect_tag(tag, MKBETAG('m', 'o', 'o', 'f')) != 0)
goto fail;
while (pos < offset + moof_size) {
pos = avio_tell(in);
size = avio_rb32(in);
tag = avio_rb32(in);
if (tag == MKBETAG('t', 'r', 'a', 'f')) {
int64_t traf_pos = pos;
int64_t traf_size = size;
while (pos < traf_pos + traf_size) {
pos = avio_tell(in);
size = avio_rb32(in);
tag = avio_rb32(in);
if (tag == MKBETAG('t', 'r', 'u', 'n')) {
return read_trun_duration(in, pos + size);
}
avio_seek(in, pos + size, SEEK_SET);
}
fprintf(stderr, "Couldn't find trun\n");
goto fail;
}
avio_seek(in, pos + size, SEEK_SET);
}
fprintf(stderr, "Couldn't find traf\n");
fail:
return ret;
}
static int read_tfra(struct Tracks *tracks, int start_index, AVIOContext *f)
{
int ret = AVERROR_EOF, track_id;
@@ -253,12 +327,7 @@ static int read_tfra(struct Tracks *tracks, int start_index, AVIOContext *f)
goto fail;
}
// The duration here is always the difference between consecutive
// start times and doesn't even try to read the actual duration of the
// media fragments. This is what other smooth streaming tools tend to
// do too, but cannot express missing fragments, and the start times
// may not match the stream metadata we get from libavformat. Correct
// calculation would require parsing the tfxd atom (if present, it's
// not mandatory) or parsing the full moof atoms separately.
// start times.
for (i = 0; i < track->chunks; i++) {
if (version == 1) {
track->offsets[i].time = avio_rb64(f);
@@ -281,6 +350,17 @@ static int read_tfra(struct Tracks *tracks, int start_index, AVIOContext *f)
track->offsets[track->chunks - 1].duration = track->offsets[0].time +
track->duration -
track->offsets[track->chunks - 1].time;
}
// Now try and read the actual durations from the trun sample data.
for (i = 0; i < track->chunks; i++) {
int64_t duration = read_moof_duration(f, track->offsets[i].offset);
if (duration > 0 && abs(duration - track->offsets[i].duration) > 3) {
// 3 allows for integer duration to drift a few units,
// e.g., for 1/3 durations
track->offsets[i].duration = duration;
}
}
if (track->chunks > 0) {
if (track->offsets[track->chunks - 1].duration <= 0) {
fprintf(stderr, "Calculated last chunk duration for track %d "
"was non-positive (%"PRId64"), probably due to missing "
@@ -575,10 +655,6 @@ static void print_track_chunks(FILE *out, struct Tracks *tracks, int main,
fprintf(out, "\t\t<c n=\"%d\" d=\"%"PRId64"\" ",
i, track->offsets[i].duration);
if (pos != track->offsets[i].time) {
// With the current logic for calculation of durations from
// chunk start times, this branch can only be hit on the first
// chunk - but that's still useful and this will keep working
// if the duration calculation is improved.
fprintf(out, "t=\"%"PRId64"\" ", track->offsets[i].time);
pos = track->offsets[i].time;
}