On 3/25/2020 1:44 AM, Andreas Rheinhardt wrote: > Up until now, writing level 1 elements proceeded as follows: First, the > element id was written to the ordinary output AVIOContext and a dynamic > buffer was opened for the content of the level 1 element in > start_ebml_master_crc32(). Then this buffer was actually used and after it > was closed (in end_ebml_master_crc32()), the size field corresponding to > the buffer's size was written, after which the actual data was written. > > This commit changes this: Nothing is written to the main AVIOContext any > more in start_ebml_master_crc32(). end_ebml_master_crc32() now writes > both the id, the length field as well as the data. This implies that > one can start a level 1 element in memory without outputting anything. > This is done to enable to test whether enough space has been reserved > for the Cues (if space has been reserved for them) before writing them. > A large duration between outputting the header and outputting the rest > could also break certain streaming usecases like the one from #8578 > (which this commit fixes). > > Signed-off-by: Andreas Rheinhardt <andreas.rheinha...@gmail.com> > --- > The commit message has been updated in light of ticket #8578; nothing > else has changed.
Should be ok. And please backport it to release/4.2 branch using git cherry-pick -x, so the commit hash from master is referenced. > > I'd like to apply this and everything until (but excluding) #18 [1] > in the coming days to fix the aforementioned issue (I will also backport > a fix to 4.2). > > [1] is the cutoff point because upon rereading I am not sure anymore > whether it is good to write the cues at the end if the reserved space > doesn't suffice and return normally afterwards, because the fact that > the cues have not been written at the front won't be detectable from the > return value of av_write_trailer() any more (one only gets a > AV_LOG_WARNING logmessage). > > [1]: https://ffmpeg.org/pipermail/ffmpeg-devel/2020-January/255157.html > > libavformat/matroskaenc.c | 60 +++++++++++++++++++++------------------ > 1 file changed, 32 insertions(+), 28 deletions(-) > > diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c > index 66f1bc4255..501d68a8f7 100644 > --- a/libavformat/matroskaenc.c > +++ b/libavformat/matroskaenc.c > @@ -325,26 +325,26 @@ static void end_ebml_master(AVIOContext *pb, > ebml_master master) > avio_seek(pb, pos, SEEK_SET); > } > > -static int start_ebml_master_crc32(AVIOContext *pb, AVIOContext **dyn_cp, > MatroskaMuxContext *mkv, > - uint32_t elementid) > +static int start_ebml_master_crc32(AVIOContext **dyn_cp, MatroskaMuxContext > *mkv) > { > int ret; > > if ((ret = avio_open_dyn_buf(dyn_cp)) < 0) > return ret; > > - put_ebml_id(pb, elementid); > if (mkv->write_crc) > put_ebml_void(*dyn_cp, 6); /* Reserve space for CRC32 so > position/size calculations using avio_tell() take it into account */ > > return 0; > } > > -static void end_ebml_master_crc32(AVIOContext *pb, AVIOContext **dyn_cp, > MatroskaMuxContext *mkv) > +static void end_ebml_master_crc32(AVIOContext *pb, AVIOContext **dyn_cp, > + MatroskaMuxContext *mkv, uint32_t id) > { > uint8_t *buf, crc[4]; > int size, skip = 0; > > + put_ebml_id(pb, id); > size = avio_close_dyn_buf(*dyn_cp, &buf); > put_ebml_num(pb, size, 0); > if (mkv->write_crc) { > @@ -362,13 +362,14 @@ static void end_ebml_master_crc32(AVIOContext *pb, > AVIOContext **dyn_cp, Matrosk > * Complete ebml master without destroying the buffer, allowing for later > updates > */ > static void end_ebml_master_crc32_preliminary(AVIOContext *pb, AVIOContext > **dyn_cp, MatroskaMuxContext *mkv, > - int64_t *pos) > + uint32_t id, int64_t *pos) > { > uint8_t *buf; > int size = avio_get_dyn_buf(*dyn_cp, &buf); > > *pos = avio_tell(pb); > > + put_ebml_id(pb, id); > put_ebml_num(pb, size, 0); > avio_write(pb, buf, size); > } > @@ -450,7 +451,7 @@ static int mkv_write_seekhead(AVIOContext *pb, > MatroskaMuxContext *mkv, > goto seek; > } > > - ret = start_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_SEEKHEAD); > + ret = start_ebml_master_crc32(&dyn_cp, mkv); > if (ret < 0) > return ret; > > @@ -466,7 +467,7 @@ static int mkv_write_seekhead(AVIOContext *pb, > MatroskaMuxContext *mkv, > put_ebml_uint(dyn_cp, MATROSKA_ID_SEEKPOSITION, entry->segmentpos); > end_ebml_master(dyn_cp, seekentry); > } > - end_ebml_master_crc32(pb, &dyn_cp, mkv); > + end_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_SEEKHEAD); > > remaining = seekhead->filepos + seekhead->reserved_size - avio_tell(pb); > put_ebml_void(pb, remaining); > @@ -510,7 +511,7 @@ static int64_t mkv_write_cues(AVFormatContext *s, > mkv_cues *cues, mkv_track *tra > int ret; > > currentpos = avio_tell(pb); > - ret = start_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_CUES); > + ret = start_ebml_master_crc32(&dyn_cp, mkv); > if (ret < 0) > return ret; > > @@ -553,7 +554,7 @@ static int64_t mkv_write_cues(AVFormatContext *s, > mkv_cues *cues, mkv_track *tra > ffio_reset_dyn_buf(cuepoint); > } > ffio_free_dyn_buf(&cuepoint); > - end_ebml_master_crc32(pb, &dyn_cp, mkv); > + end_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_CUES); > > return currentpos; > } > @@ -1375,7 +1376,7 @@ static int mkv_write_tracks(AVFormatContext *s) > > mkv_add_seekhead_entry(mkv, MATROSKA_ID_TRACKS, avio_tell(pb)); > > - ret = start_ebml_master_crc32(pb, &mkv->tracks_bc, mkv, > MATROSKA_ID_TRACKS); > + ret = start_ebml_master_crc32(&mkv->tracks_bc, mkv); > if (ret < 0) > return ret; > > @@ -1390,9 +1391,10 @@ static int mkv_write_tracks(AVFormatContext *s) > } > > if ((pb->seekable & AVIO_SEEKABLE_NORMAL) && !mkv->is_live) > - end_ebml_master_crc32_preliminary(pb, &mkv->tracks_bc, mkv, > &mkv->tracks_pos); > + end_ebml_master_crc32_preliminary(pb, &mkv->tracks_bc, mkv, > + MATROSKA_ID_TRACKS, > &mkv->tracks_pos); > else > - end_ebml_master_crc32(pb, &mkv->tracks_bc, mkv); > + end_ebml_master_crc32(pb, &mkv->tracks_bc, mkv, MATROSKA_ID_TRACKS); > > return 0; > } > @@ -1410,7 +1412,7 @@ static int mkv_write_chapters(AVFormatContext *s) > > mkv_add_seekhead_entry(mkv, MATROSKA_ID_CHAPTERS, avio_tell(pb)); > > - ret = start_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_CHAPTERS); > + ret = start_ebml_master_crc32(&dyn_cp, mkv); > if (ret < 0) return ret; > > editionentry = start_ebml_master(dyn_cp, MATROSKA_ID_EDITIONENTRY, 0); > @@ -1448,7 +1450,7 @@ static int mkv_write_chapters(AVFormatContext *s) > end_ebml_master(dyn_cp, chapteratom); > } > end_ebml_master(dyn_cp, editionentry); > - end_ebml_master_crc32(pb, &dyn_cp, mkv); > + end_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_CHAPTERS); > > mkv->wrote_chapters = 1; > return 0; > @@ -1499,7 +1501,7 @@ static int mkv_write_tag_targets(AVFormatContext *s, > uint32_t elementid, > if (!mkv->tags_bc) { > mkv_add_seekhead_entry(mkv, MATROSKA_ID_TAGS, avio_tell(s->pb)); > > - ret = start_ebml_master_crc32(s->pb, &mkv->tags_bc, mkv, > MATROSKA_ID_TAGS); > + ret = start_ebml_master_crc32(&mkv->tags_bc, mkv); > if (ret < 0) > return ret; > } > @@ -1644,9 +1646,10 @@ static int mkv_write_tags(AVFormatContext *s) > > if (mkv->tags_bc) { > if ((s->pb->seekable & AVIO_SEEKABLE_NORMAL) && !mkv->is_live) > - end_ebml_master_crc32_preliminary(s->pb, &mkv->tags_bc, mkv, > &mkv->tags_pos); > + end_ebml_master_crc32_preliminary(s->pb, &mkv->tags_bc, mkv, > + MATROSKA_ID_TAGS, > &mkv->tags_pos); > else > - end_ebml_master_crc32(s->pb, &mkv->tags_bc, mkv); > + end_ebml_master_crc32(s->pb, &mkv->tags_bc, mkv, > MATROSKA_ID_TAGS); > } > return 0; > } > @@ -1669,7 +1672,7 @@ static int mkv_write_attachments(AVFormatContext *s) > > mkv_add_seekhead_entry(mkv, MATROSKA_ID_ATTACHMENTS, avio_tell(pb)); > > - ret = start_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_ATTACHMENTS); > + ret = start_ebml_master_crc32(&dyn_cp, mkv); > if (ret < 0) return ret; > > for (i = 0; i < s->nb_streams; i++) { > @@ -1742,7 +1745,7 @@ static int mkv_write_attachments(AVFormatContext *s) > mkv->attachments->entries[mkv->attachments->num_entries].stream_idx > = i; > mkv->attachments->entries[mkv->attachments->num_entries++].fileuid > = fileuid; > } > - end_ebml_master_crc32(pb, &dyn_cp, mkv); > + end_ebml_master_crc32(pb, &dyn_cp, mkv, MATROSKA_ID_ATTACHMENTS); > > return 0; > } > @@ -1821,7 +1824,7 @@ static int mkv_write_header(AVFormatContext *s) > > mkv_add_seekhead_entry(mkv, MATROSKA_ID_INFO, avio_tell(pb)); > > - ret = start_ebml_master_crc32(pb, &mkv->info_bc, mkv, MATROSKA_ID_INFO); > + ret = start_ebml_master_crc32(&mkv->info_bc, mkv); > if (ret < 0) > return ret; > pb = mkv->info_bc; > @@ -1880,9 +1883,10 @@ static int mkv_write_header(AVFormatContext *s) > } > } > if ((s->pb->seekable & AVIO_SEEKABLE_NORMAL) && !mkv->is_live) > - end_ebml_master_crc32_preliminary(s->pb, &mkv->info_bc, mkv, > &mkv->info_pos); > + end_ebml_master_crc32_preliminary(s->pb, &mkv->info_bc, mkv, > + MATROSKA_ID_INFO, &mkv->info_pos); > else > - end_ebml_master_crc32(s->pb, &mkv->info_bc, mkv); > + end_ebml_master_crc32(s->pb, &mkv->info_bc, mkv, MATROSKA_ID_INFO); > pb = s->pb; > > ret = mkv_write_tracks(s); > @@ -2170,7 +2174,7 @@ static void mkv_end_cluster(AVFormatContext *s) > { > MatroskaMuxContext *mkv = s->priv_data; > > - end_ebml_master_crc32(s->pb, &mkv->cluster_bc, mkv); > + end_ebml_master_crc32(s->pb, &mkv->cluster_bc, mkv, MATROSKA_ID_CLUSTER); > mkv->cluster_pos = -1; > avio_write_marker(s->pb, AV_NOPTS_VALUE, AVIO_DATA_MARKER_FLUSH_POINT); > } > @@ -2311,7 +2315,7 @@ static int mkv_write_packet_internal(AVFormatContext > *s, AVPacket *pkt, int add_ > > if (mkv->cluster_pos == -1) { > mkv->cluster_pos = avio_tell(s->pb); > - ret = start_ebml_master_crc32(s->pb, &mkv->cluster_bc, mkv, > MATROSKA_ID_CLUSTER); > + ret = start_ebml_master_crc32(&mkv->cluster_bc, mkv); > if (ret < 0) > return ret; > put_ebml_uint(mkv->cluster_bc, MATROSKA_ID_CLUSTERTIMECODE, FFMAX(0, > ts)); > @@ -2477,7 +2481,7 @@ static int mkv_write_trailer(AVFormatContext *s) > } > > if (mkv->cluster_bc) { > - end_ebml_master_crc32(pb, &mkv->cluster_bc, mkv); > + end_ebml_master_crc32(pb, &mkv->cluster_bc, mkv, > MATROSKA_ID_CLUSTER); > } > > ret = mkv_write_chapters(s); > @@ -2525,11 +2529,11 @@ static int mkv_write_trailer(AVFormatContext *s) > av_log(s, AV_LOG_DEBUG, "end duration = %" PRIu64 "\n", > mkv->duration); > avio_seek(mkv->info_bc, mkv->duration_offset, SEEK_SET); > put_ebml_float(mkv->info_bc, MATROSKA_ID_DURATION, mkv->duration); > - end_ebml_master_crc32(pb, &mkv->info_bc, mkv); > + end_ebml_master_crc32(pb, &mkv->info_bc, mkv, MATROSKA_ID_INFO); > > // write tracks master > avio_seek(pb, mkv->tracks_pos, SEEK_SET); > - end_ebml_master_crc32(pb, &mkv->tracks_bc, mkv); > + end_ebml_master_crc32(pb, &mkv->tracks_bc, mkv, MATROSKA_ID_TRACKS); > > // update stream durations > if (!mkv->is_live) { > @@ -2559,7 +2563,7 @@ static int mkv_write_trailer(AVFormatContext *s) > } > if (mkv->tags_bc && !mkv->is_live) { > avio_seek(pb, mkv->tags_pos, SEEK_SET); > - end_ebml_master_crc32(pb, &mkv->tags_bc, mkv); > + end_ebml_master_crc32(pb, &mkv->tags_bc, mkv, MATROSKA_ID_TAGS); > } > > avio_seek(pb, currentpos, SEEK_SET); > _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
