[FFmpeg-devel] [PATCH] avformat/mpegts: skip non-PMT tids earlier

Aman Gupta ffmpeg at tmm1.net
Wed May 9 01:20:32 EEST 2018

From: Aman Gupta <aman at tmm1.net>

This mimics the logic flow in all the other callbacks
(pat_cb, sdt_cb, m4sl_cb), and avoids calling skip_identical()
for non PMT_TID packets.

Since skip_identical modifies internal state like
MpegTSSectionFilter.last_ver, this change prevents unnecessary
reprocessing on some streams which contain multiple tables in
the PMT pid. This can be observed with streams from certain US
cable providers, which include both tid=0x2 and another unspecified
 libavformat/mpegts.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
index 629631f60a..5c9ff73133 100644
--- a/libavformat/mpegts.c
+++ b/libavformat/mpegts.c
@@ -2000,14 +2000,14 @@ static void pmt_cb(MpegTSFilter *filter, const uint8_t *section, int section_len
     p = section;
     if (parse_section_header(h, &p, p_end) < 0)
+    if (h->tid != PMT_TID)
+        return;
     if (skip_identical(h, tssf))
     av_log(ts->stream, AV_LOG_TRACE, "sid=0x%x sec_num=%d/%d version=%d tid=%d\n",
             h->id, h->sec_num, h->last_sec_num, h->version, h->tid);
-    if (h->tid != PMT_TID)
-        return;
     if (!ts->scan_all_pmts && ts->skip_changes)

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