[FFmpeg-cvslog] avformat/yuv4mpegdec: simplify math

Paul B Mahol git at videolan.org
Thu May 3 15:32:52 EEST 2018 

ffmpeg | branch: master | Paul B Mahol <onemda at gmail.com> | Tue May  1 17:46:08 2018 +0200| [5abcf45d752df0a3f654833272eb0d7aae34d431] | committer: Paul B Mahol

avformat/yuv4mpegdec: simplify math

This one actually works with hd1080 y4m files when seeking backwards.

Signed-off-by: Paul B Mahol <onemda at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=5abcf45d752df0a3f654833272eb0d7aae34d431
---

 libavformat/yuv4mpegdec.c    |  9 +++----
 tests/ref/seek/lavf-yuv4mpeg | 57 ++++++++++++++++++++++----------------------
 2 files changed, 32 insertions(+), 34 deletions(-)

diff --git a/libavformat/yuv4mpegdec.c b/libavformat/yuv4mpegdec.c
index 8662a42a4c..eff7fc518e 100644
--- a/libavformat/yuv4mpegdec.c
+++ b/libavformat/yuv4mpegdec.c
@@ -314,14 +314,11 @@ static int yuv4_read_packet(AVFormatContext *s, AVPacket *pkt)
 static int yuv4_read_seek(AVFormatContext *s, int stream_index,
                           int64_t pts, int flags)
 {
-    AVStream *st = s->streams[0];
     int64_t pos;
 
-    pos = av_rescale_rnd(pts * s->packet_size,
-                         st->time_base.num,
-                         st->time_base.den * s->packet_size,
-                         (flags & AVSEEK_FLAG_BACKWARD) ? AV_ROUND_DOWN : AV_ROUND_UP);
-    pos *= s->packet_size;
+    if (flags & AVSEEK_FLAG_BACKWARD)
+        pts = FFMAX(0, pts - 1);
+    pos = pts * s->packet_size;
 
     if (avio_seek(s->pb, pos + s->internal->data_offset, SEEK_SET) < 0)
         return -1;
diff --git a/tests/ref/seek/lavf-yuv4mpeg b/tests/ref/seek/lavf-yuv4mpeg
index 15d4d8c8c1..c416b4657b 100644
--- a/tests/ref/seek/lavf-yuv4mpeg
+++ b/tests/ref/seek/lavf-yuv4mpeg
@@ -1,48 +1,49 @@
 ret: 0         st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos:     64 size:152064
 ret:-1         st:-1 flags:0  ts:-1.000000
 ret: 0         st:-1 flags:1  ts: 1.894167
-ret: 0         st: 0 flags:1 dts: 0.040000 pts: 0.040000 pos: 152134 size:152064
+ret:-EOF
 ret: 0         st: 0 flags:0  ts: 0.800000
-ret: 0         st: 0 flags:1 dts: 0.040000 pts: 0.040000 pos: 152134 size:152064
-ret:-1         st: 0 flags:1  ts:-0.320000
+ret: 0         st: 0 flags:1 dts: 0.800000 pts: 0.800000 pos:3041464 size:152064
+ret: 0         st: 0 flags:1  ts:-0.320000
+ret: 0         st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos:     64 size:152064
 ret: 0         st:-1 flags:0  ts: 2.576668
-ret: 0         st: 0 flags:1 dts: 0.120000 pts: 0.120000 pos: 456274 size:152064
+ret:-EOF
 ret: 0         st:-1 flags:1  ts: 1.470835
-ret: 0         st: 0 flags:1 dts: 0.040000 pts: 0.040000 pos: 152134 size:152064
+ret:-EOF
 ret: 0         st: 0 flags:0  ts: 0.360000
-ret: 0         st: 0 flags:1 dts: 0.040000 pts: 0.040000 pos: 152134 size:152064
-ret:-1         st: 0 flags:1  ts:-0.760000
+ret: 0         st: 0 flags:1 dts: 0.360000 pts: 0.360000 pos:1368694 size:152064
+ret: 0         st: 0 flags:1  ts:-0.760000
+ret: 0         st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos:     64 size:152064
 ret: 0         st:-1 flags:0  ts: 2.153336
-ret: 0         st: 0 flags:1 dts: 0.120000 pts: 0.120000 pos: 456274 size:152064
+ret:-EOF
 ret: 0         st:-1 flags:1  ts: 1.047503
-ret: 0         st: 0 flags:1 dts: 0.040000 pts: 0.040000 pos: 152134 size:152064
-ret: 0         st: 0 flags:0  ts:-0.040000
-ret: 0         st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos:     64 size:152064
+ret:-EOF
+ret:-1         st: 0 flags:0  ts:-0.040000
 ret: 0         st: 0 flags:1  ts: 2.840000
-ret: 0         st: 0 flags:1 dts: 0.080000 pts: 0.080000 pos: 304204 size:152064
+ret:-EOF
 ret: 0         st:-1 flags:0  ts: 1.730004
-ret: 0         st: 0 flags:1 dts: 0.080000 pts: 0.080000 pos: 304204 size:152064
+ret:-EOF
 ret: 0         st:-1 flags:1  ts: 0.624171
-ret: 0         st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos:     64 size:152064
-ret: 0         st: 0 flags:0  ts:-0.480000
-ret: 0         st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos:     64 size:152064
+ret: 0         st: 0 flags:1 dts: 0.600000 pts: 0.600000 pos:2281114 size:152064
+ret:-1         st: 0 flags:0  ts:-0.480000
 ret: 0         st: 0 flags:1  ts: 2.400000
-ret: 0         st: 0 flags:1 dts: 0.080000 pts: 0.080000 pos: 304204 size:152064
+ret:-EOF
 ret: 0         st:-1 flags:0  ts: 1.306672
-ret: 0         st: 0 flags:1 dts: 0.080000 pts: 0.080000 pos: 304204 size:152064
+ret:-EOF
 ret: 0         st:-1 flags:1  ts: 0.200839
-ret: 0         st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos:     64 size:152064
-ret: 0         st: 0 flags:0  ts:-0.920000
-ret: 0         st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos:     64 size:152064
+ret: 0         st: 0 flags:1 dts: 0.160000 pts: 0.160000 pos: 608344 size:152064
+ret:-1         st: 0 flags:0  ts:-0.920000
 ret: 0         st: 0 flags:1  ts: 2.000000
-ret: 0         st: 0 flags:1 dts: 0.080000 pts: 0.080000 pos: 304204 size:152064
+ret:-EOF
 ret: 0         st:-1 flags:0  ts: 0.883340
-ret: 0         st: 0 flags:1 dts: 0.040000 pts: 0.040000 pos: 152134 size:152064
-ret:-1         st:-1 flags:1  ts:-0.222493
+ret: 0         st: 0 flags:1 dts: 0.880000 pts: 0.880000 pos:3345604 size:152064
+ret: 0         st:-1 flags:1  ts:-0.222493
+ret: 0         st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos:     64 size:152064
 ret: 0         st: 0 flags:0  ts: 2.680000
-ret: 0         st: 0 flags:1 dts: 0.120000 pts: 0.120000 pos: 456274 size:152064
+ret:-EOF
 ret: 0         st: 0 flags:1  ts: 1.560000
-ret: 0         st: 0 flags:1 dts: 0.040000 pts: 0.040000 pos: 152134 size:152064
+ret:-EOF
 ret: 0         st:-1 flags:0  ts: 0.460008
-ret: 0         st: 0 flags:1 dts: 0.040000 pts: 0.040000 pos: 152134 size:152064
-ret:-1         st:-1 flags:1  ts:-0.645825
+ret: 0         st: 0 flags:1 dts: 0.480000 pts: 0.480000 pos:1824904 size:152064
+ret: 0         st:-1 flags:1  ts:-0.645825
+ret: 0         st: 0 flags:1 dts: 0.000000 pts: 0.000000 pos:     64 size:152064

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