From 8e4c871196adfb16adf64f826c1291a4b0b0af4f Mon Sep 17 00:00:00 2001 From: Andreas Rheinhardt Date: Sun, 29 Dec 2019 10:15:19 +0100 Subject: [PATCH] avformat/matroskaenc: Avoid seek when writing Cues at the front When the Cues are written in front of the Cluster, the muxer would seek to the beginning (to where the Cues ought to be written) and write the Cues; afterwards it would seek back to the end of the file only to seek to the beginning once again to update several elements there. This commit removes the seek to the end. Signed-off-by: Andreas Rheinhardt --- libavformat/matroskaenc.c | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) diff --git a/libavformat/matroskaenc.c b/libavformat/matroskaenc.c index d1edc6756e..796383320f 100644 --- a/libavformat/matroskaenc.c +++ b/libavformat/matroskaenc.c @@ -2456,7 +2456,6 @@ static int mkv_write_trailer(AVFormatContext *s) { MatroskaMuxContext *mkv = s->priv_data; AVIOContext *pb = s->pb; - int64_t currentpos; int ret; // check if we have an audio packet cached @@ -2479,11 +2478,14 @@ static int mkv_write_trailer(AVFormatContext *s) if ((pb->seekable & AVIO_SEEKABLE_NORMAL) && !mkv->is_live) { - int64_t ret64; + int64_t endpos, ret64; + + endpos = avio_tell(pb); if (mkv->cues.num_entries) { AVIOContext *cues; uint64_t size; + int64_t cuespos = endpos; int length_size = 0; ret = start_ebml_master_crc32(&cues, mkv); @@ -2510,7 +2512,7 @@ static int mkv_write_trailer(AVFormatContext *s) ffio_free_dyn_buf(&cues); goto after_cues; } else { - currentpos = avio_tell(pb); + cuespos = mkv->cues_pos; if ((ret64 = avio_seek(pb, mkv->cues_pos, SEEK_SET)) < 0) { ffio_free_dyn_buf(&cues); return ret64; @@ -2526,18 +2528,16 @@ static int mkv_write_trailer(AVFormatContext *s) } } } - mkv_add_seekhead_entry(mkv, MATROSKA_ID_CUES, avio_tell(pb)); + mkv_add_seekhead_entry(mkv, MATROSKA_ID_CUES, cuespos); end_ebml_master_crc32(pb, &cues, mkv, MATROSKA_ID_CUES, length_size); if (mkv->reserve_cues_space) { if (size < mkv->reserve_cues_space) put_ebml_void(pb, mkv->reserve_cues_space - size); - avio_seek(pb, currentpos, SEEK_SET); - } + } else + endpos = avio_tell(pb); } after_cues: - currentpos = avio_tell(pb); - ret = mkv_write_seekhead(pb, mkv, 1, mkv->info_pos); if (ret < 0) return ret; @@ -2583,7 +2583,7 @@ static int mkv_write_trailer(AVFormatContext *s) end_ebml_master_crc32(pb, &mkv->tags_bc, mkv, MATROSKA_ID_TAGS, 0); } - avio_seek(pb, currentpos, SEEK_SET); + avio_seek(pb, endpos, SEEK_SET); } if (!mkv->is_live) {