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lavf/mov.c: Make audio timestamps strictly monotonically increasing inside an edit list.
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
Michael Niedermayer
parent
7e0235bdb1
commit
dba2db6c0e
@ -2855,6 +2855,21 @@ static int64_t add_index_entry(AVStream *st, int64_t pos, int64_t timestamp,
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return index;
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}
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/**
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* Rewrite timestamps of index entries in the range [end_index - frame_duration_buffer_size, end_index)
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* by subtracting end_ts successively by the amounts given in frame_duration_buffer.
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*/
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static void fix_index_entry_timestamps(AVStream* st, int end_index, int64_t end_ts,
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int64_t* frame_duration_buffer,
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int frame_duration_buffer_size) {
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int i = 0;
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av_assert0(end_index >= 0 && end_index <= st->nb_index_entries);
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for (i = 0; i < frame_duration_buffer_size; i++) {
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end_ts -= frame_duration_buffer[frame_duration_buffer_size - 1 - i];
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st->index_entries[end_index - 1 - i].timestamp = end_ts;
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}
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}
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/**
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* Append a new ctts entry to ctts_data.
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* Returns the new ctts_count if successful, else returns -1.
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@ -2919,7 +2934,10 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
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int64_t edit_list_media_time_dts = 0;
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int64_t edit_list_start_encountered = 0;
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int64_t search_timestamp = 0;
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int64_t* frame_duration_buffer = NULL;
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int num_discarded_begin = 0;
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int first_non_zero_audio_edit = -1;
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int packet_skip_samples = 0;
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if (!msc->elst_data || msc->elst_count <= 0) {
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return;
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@ -2955,6 +2973,7 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
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edit_list_index++;
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edit_list_dts_counter = edit_list_dts_entry_end;
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edit_list_dts_entry_end += edit_list_duration;
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num_discarded_begin = 0;
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if (edit_list_media_time == -1) {
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continue;
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}
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@ -2962,7 +2981,14 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
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// If we encounter a non-negative edit list reset the skip_samples/start_pad fields and set them
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// according to the edit list below.
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if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
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st->skip_samples = msc->start_pad = 0;
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if (first_non_zero_audio_edit < 0) {
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first_non_zero_audio_edit = 1;
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} else {
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first_non_zero_audio_edit = 0;
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}
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if (first_non_zero_audio_edit > 0)
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st->skip_samples = msc->start_pad = 0;
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}
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//find closest previous key frame
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@ -3041,24 +3067,56 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
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}
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if (curr_cts < edit_list_media_time || curr_cts >= (edit_list_duration + edit_list_media_time)) {
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if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO && curr_cts < edit_list_media_time &&
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curr_cts + frame_duration > edit_list_media_time &&
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st->skip_samples == 0 && msc->start_pad == 0) {
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st->skip_samples = msc->start_pad = edit_list_media_time - curr_cts;
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if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO && st->codecpar->codec_id != AV_CODEC_ID_VORBIS &&
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curr_cts < edit_list_media_time && curr_cts + frame_duration > edit_list_media_time &&
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first_non_zero_audio_edit > 0) {
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packet_skip_samples = edit_list_media_time - curr_cts;
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st->skip_samples += packet_skip_samples;
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// Shift the index entry timestamp by skip_samples to be correct.
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edit_list_dts_counter -= st->skip_samples;
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// Shift the index entry timestamp by packet_skip_samples to be correct.
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edit_list_dts_counter -= packet_skip_samples;
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if (edit_list_start_encountered == 0) {
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edit_list_start_encountered = 1;
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edit_list_start_encountered = 1;
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// Make timestamps strictly monotonically increasing for audio, by rewriting timestamps for
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// discarded packets.
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if (frame_duration_buffer) {
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fix_index_entry_timestamps(st, st->nb_index_entries, edit_list_dts_counter,
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frame_duration_buffer, num_discarded_begin);
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av_freep(&frame_duration_buffer);
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}
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}
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av_log(mov->fc, AV_LOG_DEBUG, "skip %d audio samples from curr_cts: %"PRId64"\n", st->skip_samples, curr_cts);
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av_log(mov->fc, AV_LOG_DEBUG, "skip %d audio samples from curr_cts: %"PRId64"\n", packet_skip_samples, curr_cts);
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} else {
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flags |= AVINDEX_DISCARD_FRAME;
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av_log(mov->fc, AV_LOG_DEBUG, "drop a frame at curr_cts: %"PRId64" @ %"PRId64"\n", curr_cts, index);
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if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO && edit_list_start_encountered == 0) {
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num_discarded_begin++;
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frame_duration_buffer = av_realloc(frame_duration_buffer,
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num_discarded_begin * sizeof(int64_t));
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if (!frame_duration_buffer) {
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av_log(mov->fc, AV_LOG_ERROR, "Cannot reallocate frame duration buffer\n");
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break;
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}
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frame_duration_buffer[num_discarded_begin - 1] = frame_duration;
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// Increment skip_samples for the first non-zero audio edit list
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if (first_non_zero_audio_edit > 0 && st->codecpar->codec_id != AV_CODEC_ID_VORBIS) {
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st->skip_samples += frame_duration;
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msc->start_pad = st->skip_samples;
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}
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}
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}
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} else if (edit_list_start_encountered == 0) {
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edit_list_start_encountered = 1;
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// Make timestamps strictly monotonically increasing for audio, by rewriting timestamps for
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// discarded packets.
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if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO && frame_duration_buffer) {
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fix_index_entry_timestamps(st, st->nb_index_entries, edit_list_dts_counter,
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frame_duration_buffer, num_discarded_begin);
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av_freep(&frame_duration_buffer);
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}
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}
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if (add_index_entry(st, current->pos, edit_list_dts_counter, current->size,
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@ -7,7 +7,7 @@ duration_ts=103326
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start_time=0.000000
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duration=2.367000
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[/FORMAT]
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packet|pts=0|dts=0|duration=N/A
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packet|pts=-1024|dts=-1024|duration=1024
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packet|pts=0|dts=0|duration=1024
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packet|pts=1024|dts=1024|duration=1024
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packet|pts=2048|dts=2048|duration=1024
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@ -7,7 +7,7 @@ duration_ts=529200
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start_time=0.000000
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duration=12.024000
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[/FORMAT]
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packet|pts=0|dts=0|duration=N/A
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packet|pts=-1024|dts=-1024|duration=1024
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packet|pts=0|dts=0|duration=1024
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packet|pts=1024|dts=1024|duration=1024
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packet|pts=2048|dts=2048|duration=1024
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