[FFmpeg-devel] [PATCH] lavf/mov.c: Offset index timestamps by the minimum pts to make first pts zero.
wm4
nfxjfg at googlemail.com
Sat Jun 3 15:40:55 EEST 2017
On Fri, 2 Jun 2017 18:17:22 -0700
Sasi Inguva <isasi-at-google.com at ffmpeg.org> wrote:
> Fixes t/6421
>
> Signed-off-by: Sasi Inguva <isasi at google.com>
> ---
> libavformat/mov.c | 57 ++++++++++++++++++++++++----------
> tests/ref/fate/h264-twofields-packet | 60 ++++++++++++++++++------------------
> 2 files changed, 70 insertions(+), 47 deletions(-)
>
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 3845e63b53..d7d64c3361 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -3039,6 +3039,9 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
> int64_t edit_list_dts_entry_end = 0;
> int64_t edit_list_start_ctts_sample = 0;
> int64_t curr_cts;
> + int64_t curr_ctts = 0;
> + int64_t min_corrected_pts = -1;
> + int64_t empty_edits_sum_duration = 0;
> int64_t edit_list_index = 0;
> int64_t index;
> int64_t index_ctts_count;
> @@ -3053,6 +3056,7 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
> int first_non_zero_audio_edit = -1;
> int packet_skip_samples = 0;
> MOVIndexRange *current_index_range;
> + int i;
>
> if (!msc->elst_data || msc->elst_count <= 0 || nb_old <= 0) {
> return;
> @@ -3080,13 +3084,9 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
>
> // If the dts_shift is positive (in case of negative ctts values in mov),
> // then negate the DTS by dts_shift
> - if (msc->dts_shift > 0)
> + if (msc->dts_shift > 0) {
> edit_list_dts_entry_end -= msc->dts_shift;
> -
> - // Offset the DTS by ctts[0] to make the PTS of the first frame 0
> - if (ctts_data_old && ctts_count_old > 0) {
> - edit_list_dts_entry_end -= ctts_data_old[0].duration;
> - av_log(mov->fc, AV_LOG_DEBUG, "Offset DTS by ctts[%d].duration: %d\n", 0, ctts_data_old[0].duration);
> + av_log(mov->fc, AV_LOG_DEBUG, "Shifting DTS by %d because of negative CTTS.\n", msc->dts_shift);
> }
>
> start_dts = edit_list_dts_entry_end;
> @@ -3100,6 +3100,7 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
> edit_list_dts_entry_end += edit_list_duration;
> num_discarded_begin = 0;
> if (edit_list_media_time == -1) {
> + empty_edits_sum_duration += edit_list_duration;
> continue;
> }
>
> @@ -3179,11 +3180,13 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
>
> // frames (pts) before or after edit list
> curr_cts = current->timestamp + msc->dts_shift;
> + curr_ctts = 0;
>
> if (ctts_data_old && ctts_index_old < ctts_count_old) {
> - av_log(mov->fc, AV_LOG_DEBUG, "shifted frame pts, curr_cts: %"PRId64" @ %"PRId64", ctts: %d, ctts_count: %"PRId64"\n",
> - curr_cts, ctts_index_old, ctts_data_old[ctts_index_old].duration, ctts_count_old);
> - curr_cts += ctts_data_old[ctts_index_old].duration;
> + curr_ctts = ctts_data_old[ctts_index_old].duration;
> + av_log(mov->fc, AV_LOG_DEBUG, "stts: %"PRId64" ctts: %"PRId64", ctts_index: %"PRId64", ctts_count: %"PRId64"\n",
> + curr_cts, curr_ctts, ctts_index_old, ctts_count_old);
> + curr_cts += curr_ctts;
> ctts_sample_old++;
> if (ctts_sample_old == ctts_data_old[ctts_index_old].count) {
> if (add_ctts_entry(&msc->ctts_data, &msc->ctts_count,
> @@ -3244,14 +3247,21 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
> }
> }
> }
> - } 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);
> + } else {
> + if (min_corrected_pts < 0) {
> + min_corrected_pts = edit_list_dts_counter + curr_ctts + msc->dts_shift;
> + } else {
> + min_corrected_pts = FFMIN(min_corrected_pts, edit_list_dts_counter + curr_ctts + msc->dts_shift);
> + }
> + 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);
> + }
> }
> }
>
> @@ -3292,6 +3302,19 @@ static void mov_fix_index(MOVContext *mov, AVStream *st)
> }
> }
> }
> + // If there are empty edits, then min_corrected_pts might be positive intentionally. So we subtract the
> + // sum duration of emtpy edits here.
> + min_corrected_pts -= empty_edits_sum_duration;
> +
> + // If the minimum pts turns out to be greater than zero after fixing the index, then we subtract the
> + // dts by that amount to make the first pts zero.
> + if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO && min_corrected_pts > 0) {
> + av_log(mov->fc, AV_LOG_DEBUG, "Offset DTS by %"PRId64" to make first pts zero.\n", min_corrected_pts);
> + for (i = 0; i < st->nb_index_entries; ++i) {
> + st->index_entries[i].timestamp -= min_corrected_pts;
> + }
> + }
> +
> // Update av stream length
> st->duration = edit_list_dts_entry_end - start_dts;
>
> diff --git a/tests/ref/fate/h264-twofields-packet b/tests/ref/fate/h264-twofields-packet
> index 4cff0a15bd..db12498f15 100644
> --- a/tests/ref/fate/h264-twofields-packet
> +++ b/tests/ref/fate/h264-twofields-packet
> @@ -3,33 +3,33 @@
> #codec_id 0: rawvideo
> #dimensions 0: 1920x1080
> #sar 0: 1/1
> -0, 0, 0, 1, 3110400, 0x40d65f69
> -0, 1, 1, 1, 3110400, 0xdcbc50bf
> -0, 2, 2, 1, 3110400, 0x73a2276a
> -0, 3, 3, 1, 3110400, 0x84a2b3c6
> -0, 4, 4, 1, 3110400, 0x7cf3b570
> -0, 5, 5, 1, 3110400, 0xa2d1e03a
> -0, 6, 6, 1, 3110400, 0x03220fb1
> -0, 7, 7, 1, 3110400, 0x89cd526a
> -0, 8, 8, 1, 3110400, 0xbb4b7531
> -0, 9, 9, 1, 3110400, 0x0a69f053
> -0, 10, 10, 1, 3110400, 0x0187994b
> -0, 11, 11, 1, 3110400, 0x26ed49fa
> -0, 12, 12, 1, 3110400, 0xbe8966d4
> -0, 13, 13, 1, 3110400, 0x248d203c
> -0, 14, 14, 1, 3110400, 0x3139c754
> -0, 15, 15, 1, 3110400, 0xf22380c4
> -0, 16, 16, 1, 3110400, 0x3e00dcc1
> -0, 17, 17, 1, 3110400, 0x8cbe2483
> -0, 18, 18, 1, 3110400, 0x6951cd63
> -0, 19, 19, 1, 3110400, 0x36aca4c5
> -0, 20, 20, 1, 3110400, 0x4d4f6fbe
> -0, 21, 21, 1, 3110400, 0x997247aa
> -0, 22, 22, 1, 3110400, 0x0fd40e06
> -0, 23, 23, 1, 3110400, 0xa10d2d67
> -0, 24, 24, 1, 3110400, 0x87c481da
> -0, 25, 25, 1, 3110400, 0xe3dca3cd
> -0, 26, 26, 1, 3110400, 0x5f77b078
> -0, 27, 27, 1, 3110400, 0xf1ddd098
> -0, 28, 28, 1, 3110400, 0xedcd1754
> -0, 29, 29, 1, 3110400, 0x14ac7153
> +0, 0, 0, 1, 3110400, 0x48e39acd
> +0, 1, 1, 1, 3110400, 0x40d65f69
> +0, 2, 2, 1, 3110400, 0xdcbc50bf
> +0, 3, 3, 1, 3110400, 0x73a2276a
> +0, 4, 4, 1, 3110400, 0x84a2b3c6
> +0, 5, 5, 1, 3110400, 0x7cf3b570
> +0, 6, 6, 1, 3110400, 0xa2d1e03a
> +0, 7, 7, 1, 3110400, 0x03220fb1
> +0, 8, 8, 1, 3110400, 0x89cd526a
> +0, 9, 9, 1, 3110400, 0xbb4b7531
> +0, 10, 10, 1, 3110400, 0x0a69f053
> +0, 11, 11, 1, 3110400, 0x0187994b
> +0, 12, 12, 1, 3110400, 0x26ed49fa
> +0, 13, 13, 1, 3110400, 0xbe8966d4
> +0, 14, 14, 1, 3110400, 0x248d203c
> +0, 15, 15, 1, 3110400, 0x3139c754
> +0, 16, 16, 1, 3110400, 0xf22380c4
> +0, 17, 17, 1, 3110400, 0x3e00dcc1
> +0, 18, 18, 1, 3110400, 0x8cbe2483
> +0, 19, 19, 1, 3110400, 0x6951cd63
> +0, 20, 20, 1, 3110400, 0x36aca4c5
> +0, 21, 21, 1, 3110400, 0x4d4f6fbe
> +0, 22, 22, 1, 3110400, 0x997247aa
> +0, 23, 23, 1, 3110400, 0x0fd40e06
> +0, 24, 24, 1, 3110400, 0xa10d2d67
> +0, 25, 25, 1, 3110400, 0x87c481da
> +0, 26, 26, 1, 3110400, 0xe3dca3cd
> +0, 27, 27, 1, 3110400, 0x5f77b078
> +0, 28, 28, 1, 3110400, 0xf1ddd098
> +0, 29, 29, 1, 3110400, 0xedcd1754
Thanks for the fix, but is there any explanation why this happens? And
why does the FATE test change?
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