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lavf/mov.c: Make audio timestamps strictly monotonically increasing inside an edit list.

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Fixes gapless decoding. Adjust skip_samples field correctly in case of DISCARDed audio frames.

Signed-off-by: Sasi Inguva <isasi@google.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Sasi Inguva 2016-09-26 09:56:26 -07:00 committed by Michael Niedermayer
parent 7e0235bdb1
commit dba2db6c0e
3 changed files with 70 additions and 12 deletions
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78
libavformat/mov.c
View File

@ -2855,6 +2855,21 @@ static int64_t add_index_entry(AVStream *st, int64_t pos, int64_t timestamp,
return index;
}
/**
* Rewrite timestamps of index entries in the range [end_index - frame_duration_buffer_size, end_index)
* by subtracting end_ts successively by the amounts given in frame_duration_buffer.
*/
static void fix_index_entry_timestamps(AVStream* st, int end_index, int64_t end_ts,
int64_t* frame_duration_buffer,
int frame_duration_buffer_size) {
int i = 0;
av_assert0(end_index >= 0 && end_index <= st->nb_index_entries);
for (i = 0; i < frame_duration_buffer_size; i++) {
end_ts -= frame_duration_buffer[frame_duration_buffer_size - 1 - i];
st->index_entries[end_index - 1 - i].timestamp = end_ts;
}
}
/**
* Append a new ctts entry to ctts_data.
* Returns the new ctts_count if successful, else returns -1.
@ -2919,7 +2934,10 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
int64_t edit_list_media_time_dts = 0;
int64_t edit_list_start_encountered = 0;
int64_t search_timestamp = 0;
int64_t* frame_duration_buffer = NULL;
int num_discarded_begin = 0;
int first_non_zero_audio_edit = -1;
int packet_skip_samples = 0;
if (!msc->elst_data || msc->elst_count <= 0) {
return;
@ -2955,6 +2973,7 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
edit_list_index++;
edit_list_dts_counter = edit_list_dts_entry_end;
edit_list_dts_entry_end += edit_list_duration;
num_discarded_begin = 0;
if (edit_list_media_time == -1) {
continue;
}
@ -2962,7 +2981,14 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
// If we encounter a non-negative edit list reset the skip_samples/start_pad fields and set them
// according to the edit list below.
if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
st->skip_samples = msc->start_pad = 0;
if (first_non_zero_audio_edit < 0) {
first_non_zero_audio_edit = 1;
} else {
first_non_zero_audio_edit = 0;
}
if (first_non_zero_audio_edit > 0)
st->skip_samples = msc->start_pad = 0;
}
//find closest previous key frame
@ -3041,24 +3067,56 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
}
if (curr_cts < edit_list_media_time || curr_cts >= (edit_list_duration + edit_list_media_time)) {
if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO && curr_cts < edit_list_media_time &&
curr_cts + frame_duration > edit_list_media_time &&
st->skip_samples == 0 && msc->start_pad == 0) {
st->skip_samples = msc->start_pad = edit_list_media_time - curr_cts;
if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO && st->codecpar->codec_id != AV_CODEC_ID_VORBIS &&
curr_cts < edit_list_media_time && curr_cts + frame_duration > edit_list_media_time &&
first_non_zero_audio_edit > 0) {
packet_skip_samples = edit_list_media_time - curr_cts;
st->skip_samples += packet_skip_samples;
// Shift the index entry timestamp by skip_samples to be correct.
edit_list_dts_counter -= st->skip_samples;
// Shift the index entry timestamp by packet_skip_samples to be correct.
edit_list_dts_counter -= packet_skip_samples;
if (edit_list_start_encountered == 0) {
edit_list_start_encountered = 1;
edit_list_start_encountered = 1;
// Make timestamps strictly monotonically increasing for audio, by rewriting timestamps for
// discarded packets.
if (frame_duration_buffer) {
fix_index_entry_timestamps(st, st->nb_index_entries, edit_list_dts_counter,
frame_duration_buffer, num_discarded_begin);
av_freep(&frame_duration_buffer);
}
}
av_log(mov->fc, AV_LOG_DEBUG, "skip %d audio samples from curr_cts: %"PRId64"\n", st->skip_samples, curr_cts);
av_log(mov->fc, AV_LOG_DEBUG, "skip %d audio samples from curr_cts: %"PRId64"\n", packet_skip_samples, curr_cts);
} else {
flags |= AVINDEX_DISCARD_FRAME;
av_log(mov->fc, AV_LOG_DEBUG, "drop a frame at curr_cts: %"PRId64" @ %"PRId64"\n", curr_cts, index);
if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO && edit_list_start_encountered == 0) {
num_discarded_begin++;
frame_duration_buffer = av_realloc(frame_duration_buffer,
num_discarded_begin * sizeof(int64_t));
if (!frame_duration_buffer) {
av_log(mov->fc, AV_LOG_ERROR, "Cannot reallocate frame duration buffer\n");
break;
}
frame_duration_buffer[num_discarded_begin - 1] = frame_duration;
// Increment skip_samples for the first non-zero audio edit list
if (first_non_zero_audio_edit > 0 && st->codecpar->codec_id != AV_CODEC_ID_VORBIS) {
st->skip_samples += frame_duration;
msc->start_pad = st->skip_samples;
}
}
}
} else if (edit_list_start_encountered == 0) {
edit_list_start_encountered = 1;
// Make timestamps strictly monotonically increasing for audio, by rewriting timestamps for
// discarded packets.
if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO && frame_duration_buffer) {
fix_index_entry_timestamps(st, st->nb_index_entries, edit_list_dts_counter,
frame_duration_buffer, num_discarded_begin);
av_freep(&frame_duration_buffer);
}
}
if (add_index_entry(st, current->pos, edit_list_dts_counter, current->size,

2
tests/ref/fate/gaplessenc-itunes-to-ipod-aac
View File

@ -7,7 +7,7 @@ duration_ts=103326
start_time=0.000000
duration=2.367000
[/FORMAT]
packet|pts=0|dts=0|duration=N/A
packet|pts=-1024|dts=-1024|duration=1024
packet|pts=0|dts=0|duration=1024
packet|pts=1024|dts=1024|duration=1024
packet|pts=2048|dts=2048|duration=1024

2
tests/ref/fate/gaplessenc-pcm-to-mov-aac
View File

@ -7,7 +7,7 @@ duration_ts=529200
start_time=0.000000
duration=12.024000
[/FORMAT]
packet|pts=0|dts=0|duration=N/A
packet|pts=-1024|dts=-1024|duration=1024
packet|pts=0|dts=0|duration=1024
packet|pts=1024|dts=1024|duration=1024
packet|pts=2048|dts=2048|duration=1024