[FFmpeg-devel] [PATCH] lavf/mov.c: Refine edit list start seek, based on PTS computed from CTTS.
Sasi Inguva
isasi at google.com
Wed Nov 1 01:45:00 EET 2017
Attaching the fate sample.
On Tue, Oct 31, 2017 at 4:42 PM, Sasi Inguva <isasi at google.com> wrote:
> Partially fixes t/6699.
> ---
> libavformat/mov.c | 125 ++++++++++++++++++++++++++++++
> +++++------------------
> tests/fate/mov.mak | 8 ++++
> 2 files changed, 90 insertions(+), 43 deletions(-)
>
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 60f0228e2d..a295445651 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -3014,34 +3014,95 @@ static int get_edit_list_entry(MOVContext *mov,
> }
>
> /**
> - * Find the closest previous frame to the timestamp, in e_old index
> + * Find the closest previous frame to the timestamp_pts, in e_old index
> * entries. Searching for just any frame / just key frames can be
> controlled by
> * last argument 'flag'.
> - * Returns the index of the entry in st->index_entries if successful,
> - * else returns -1.
> + * Here the timestamp_pts is considered to be a presentation timestamp and
> + * the timestamp of index entries are considered to be decoding
> timestamps.
> + *
> + * Returns 0 if successful in finding a frame, else returns -1.
> + * Places the found index corresponding output arg.
> + *
> + * If ctts_old is not NULL, then refines the searched entry by searching
> + * backwards from the found timestamp, to find the frame with correct PTS.
> + *
> + * Places the found ctts_index and ctts_sample in corresponding output
> args.
> */
> -static int64_t find_prev_closest_index(AVStream *st,
> - AVIndexEntry *e_old,
> - int nb_old,
> - int64_t timestamp,
> - int flag)
> +static int find_prev_closest_index(AVStream *st,
> + AVIndexEntry *e_old,
> + int nb_old,
> + MOVStts* ctts_data,
> + int64_t ctts_count,
> + int64_t timestamp_pts,
> + int flag,
> + int64_t* index,
> + int64_t* ctts_index,
> + int64_t* ctts_sample)
> {
> + MOVStreamContext *msc = st->priv_data;
> AVIndexEntry *e_keep = st->index_entries;
> int nb_keep = st->nb_index_entries;
> - int64_t found = -1;
> int64_t i = 0;
> + int64_t index_ctts_count;
> +
> + av_assert0(index);
> +
> + // If dts_shift > 0, then all the index timestamps will have to be
> offset by
> + // at least dts_shift amount to obtain PTS.
> + // Hence we decrement the searched timestamp_pts by dts_shift to find
> the closest index element.
> + if (msc->dts_shift > 0) {
> + timestamp_pts -= msc->dts_shift;
> + }
>
> st->index_entries = e_old;
> st->nb_index_entries = nb_old;
> - found = av_index_search_timestamp(st, timestamp, flag |
> AVSEEK_FLAG_BACKWARD);
> + *index = av_index_search_timestamp(st, timestamp_pts, flag |
> AVSEEK_FLAG_BACKWARD);
>
> // Keep going backwards in the index entries until the timestamp is
> the same.
> - if (found >= 0) {
> - for (i = found; i > 0 && e_old[i].timestamp == e_old[i -
> 1].timestamp;
> + if (*index >= 0) {
> + for (i = *index; i > 0 && e_old[i].timestamp == e_old[i -
> 1].timestamp;
> i--) {
> if ((flag & AVSEEK_FLAG_ANY) ||
> (e_old[i - 1].flags & AVINDEX_KEYFRAME)) {
> - found = i - 1;
> + *index = i - 1;
> + }
> + }
> + }
> +
> + // If we have CTTS then refine the search, by searching backwards
> over PTS
> + // computed by adding corresponding CTTS durations to index
> timestamps.
> + if (ctts_data && *index >= 0) {
> + av_assert0(ctts_index);
> + av_assert0(ctts_sample);
> + // Find out the ctts_index for the found frame.
> + *ctts_index = 0;
> + *ctts_sample = 0;
> + for (index_ctts_count = 0; index_ctts_count < *index;
> index_ctts_count++) {
> + if (*ctts_index < ctts_count) {
> + (*ctts_sample)++;
> + if (ctts_data[*ctts_index].count == *ctts_sample) {
> + (*ctts_index)++;
> + *ctts_sample = 0;
> + }
> + }
> + }
> +
> + while (*index >= 0 && (*ctts_index) >= 0) {
> + // Find a "key frame" with PTS <= timestamp_pts (So that we
> can decode B-frames correctly).
> + // No need to add dts_shift to the timestamp here becase
> timestamp_pts has already been
> + // compensated by dts_shift above.
> + if ((e_old[*index].timestamp + ctts_data[*ctts_index].duration)
> <= timestamp_pts &&
> + (e_old[*index].flags & AVINDEX_KEYFRAME)) {
> + break;
> + }
> +
> + (*index)--;
> + if (*ctts_sample == 0) {
> + (*ctts_index)--;
> + if (*ctts_index >= 0)
> + *ctts_sample = ctts_data[*ctts_index].count - 1;
> + } else {
> + (*ctts_sample)--;
> }
> }
> }
> @@ -3049,7 +3110,7 @@ static int64_t find_prev_closest_index(AVStream *st,
> /* restore AVStream state*/
> st->index_entries = e_keep;
> st->nb_index_entries = nb_keep;
> - return found;
> + return *index >= 0 ? 0 : -1;
> }
>
> /**
> @@ -3220,10 +3281,8 @@ static void mov_fix_index(MOVContext *mov, AVStream
> *st)
> int64_t empty_edits_sum_duration = 0;
> int64_t edit_list_index = 0;
> int64_t index;
> - int64_t index_ctts_count;
> int flags;
> int64_t start_dts = 0;
> - 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;
> @@ -3293,17 +3352,11 @@ static void mov_fix_index(MOVContext *mov,
> AVStream *st)
> st->skip_samples = msc->start_pad = 0;
> }
>
> - //find closest previous key frame
> - edit_list_media_time_dts = edit_list_media_time;
> - if (msc->dts_shift > 0) {
> - edit_list_media_time_dts -= msc->dts_shift;
> - }
> -
> // While reordering frame index according to edit list we must
> handle properly
> // the scenario when edit list entry starts from none key frame.
> // We find closest previous key frame and preserve it and
> consequent frames in index.
> // All frames which are outside edit list entry time boundaries
> will be dropped after decoding.
> - search_timestamp = edit_list_media_time_dts;
> + search_timestamp = edit_list_media_time;
> if (st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
> // Audio decoders like AAC need need a decoder delay samples
> previous to the current sample,
> // to correctly decode this frame. Hence for audio we seek to
> a frame 1 sec. before the
> @@ -3311,38 +3364,24 @@ static void mov_fix_index(MOVContext *mov,
> AVStream *st)
> search_timestamp = FFMAX(search_timestamp - msc->time_scale,
> e_old[0].timestamp);
> }
>
> - index = find_prev_closest_index(st, e_old, nb_old,
> search_timestamp, 0);
> - if (index == -1) {
> + if (find_prev_closest_index(st, e_old, nb_old, ctts_data_old,
> ctts_count_old, search_timestamp, 0,
> + &index, &ctts_index_old,
> &ctts_sample_old) < 0) {
> av_log(mov->fc, AV_LOG_WARNING,
> "st: %d edit list: %"PRId64" Missing key frame while
> searching for timestamp: %"PRId64"\n",
> st->index, edit_list_index, search_timestamp);
> - index = find_prev_closest_index(st, e_old, nb_old,
> search_timestamp, AVSEEK_FLAG_ANY);
> -
> - if (index == -1) {
> + if (find_prev_closest_index(st, e_old, nb_old, ctts_data_old,
> ctts_count_old, search_timestamp, AVSEEK_FLAG_ANY,
> + &index, &ctts_index_old,
> &ctts_sample_old) < 0) {
> av_log(mov->fc, AV_LOG_WARNING,
> "st: %d edit list %"PRId64" Cannot find an index
> entry before timestamp: %"PRId64".\n"
> "Rounding edit list media time to zero.\n",
> st->index, edit_list_index, search_timestamp);
> index = 0;
> + ctts_index_old = 0;
> + ctts_sample_old = 0;
> edit_list_media_time = 0;
> }
> }
> current = e_old + index;
> -
> - ctts_index_old = 0;
> - ctts_sample_old = 0;
> -
> - // set ctts_index properly for the found key frame
> - for (index_ctts_count = 0; index_ctts_count < index;
> index_ctts_count++) {
> - if (ctts_data_old && ctts_index_old < ctts_count_old) {
> - ctts_sample_old++;
> - if (ctts_data_old[ctts_index_old].count ==
> ctts_sample_old) {
> - ctts_index_old++;
> - ctts_sample_old = 0;
> - }
> - }
> - }
> -
> edit_list_start_ctts_sample = ctts_sample_old;
>
> // Iterate over index and arrange it according to edit list
> diff --git a/tests/fate/mov.mak b/tests/fate/mov.mak
> index 6815e4feca..01893a0767 100644
> --- a/tests/fate/mov.mak
> +++ b/tests/fate/mov.mak
> @@ -9,6 +9,7 @@ FATE_MOV = fate-mov-3elist \
> fate-mov-invalid-elst-entry-count \
> fate-mov-gpmf-remux \
> fate-mov-440hz-10ms \
> + fate-mov-ibi-elst-starts-b \
>
> FATE_MOV_FFPROBE = fate-mov-aac-2048-priming \
> fate-mov-zombie \
> @@ -47,6 +48,13 @@ fate-mov-440hz-10ms: CMD = framemd5 -i
> $(TARGET_SAMPLES)/mov/440hz-10ms.m4a
> # Makes sure that we handle invalid edit list entry count correctly.
> fate-mov-invalid-elst-entry-count: CMD = framemd5 -flags +bitexact -i
> $(TARGET_SAMPLES)/mov/invalid_elst_entry_count.mov
>
> +# Makes sure that 1st key-frame is picked when,
> +# i) One B-frame between 2 key-frames
> +# ii) Edit list starts on B-frame.
> +# iii) Both key-frames have their DTS < edit list start
> +# i.e. Pts Order: I-B-I
> +fate-mov-ibi-elst-starts-b: CMD = framemd5 -flags +bitexact -i
> $(TARGET_SAMPLES)/mov/mov_ibi_elst_starts_b.mov
> +
> fate-mov-aac-2048-priming: CMD = run ffprobe$(PROGSSUF)$(EXESUF)
> -show_packets -print_format compact $(TARGET_SAMPLES)/mov/aac-
> 2048-priming.mov
>
> fate-mov-zombie: CMD = run ffprobe$(PROGSSUF)$(EXESUF) -show_streams
> -show_packets -show_frames -bitexact -print_format compact
> $(TARGET_SAMPLES)/mov/white_zombie_scrunch-part.mov
> --
> 2.15.0.403.gc27cc4dac6-goog
>
>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: mov_ibi_elst_starts_b.mov
Type: video/quicktime
Size: 87059 bytes
Desc: not available
URL: <http://ffmpeg.org/pipermail/ffmpeg-devel/attachments/20171031/60fcf666/attachment.mov>
More information about the ffmpeg-devel
mailing list