[FFmpeg-cvslog] ffmpeg: add option to control copying of frames prior to start.

[Michael Niedermayer]

ffmpeg | branch: master | Michael Niedermayer <michaelni at gmx.at> | Thu Sep 27 03:37:27 2012 +0200| [65f7aee63b6283a2336d03046faa37f2391d98e0] | committer: Michael Niedermayer

ffmpeg: add option to control copying of frames prior to start.

Normally we discard things prior to the intended start
for stream copy this is not always possible, and its not done by default
this option allows discarding to be enabled

this is primarely usefull when transcoding a video and stream copying an
audio stream.

Signed-off-by: Michael Niedermayer <michaelni at gmx.at>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=65f7aee63b6283a2336d03046faa37f2391d98e0
---

 ffmpeg.c     |    4 ++++
 ffmpeg.h     |    3 +++
 ffmpeg_opt.c |    5 +++++
 3 files changed, 12 insertions(+)

diff --git a/ffmpeg.c b/ffmpeg.c
index 7621e9d..3eb15a6 100644
--- a/ffmpeg.c
+++ b/ffmpeg.c
@@ -1340,6 +1340,10 @@ static void do_streamcopy(InputStream *ist, OutputStream *ost, const AVPacket *p
         !ost->copy_initial_nonkeyframes)
         return;
 
+    if (!ost->frame_number && ist->pts < of->start_time &&
+        !ost->copy_prior_start)
+        return;
+
     if (of->recording_time != INT64_MAX &&
         ist->pts >= of->recording_time + of->start_time) {
         close_output_stream(ost);
diff --git a/ffmpeg.h b/ffmpeg.h
index 85a11a0..56f8dfc 100644
--- a/ffmpeg.h
+++ b/ffmpeg.h
@@ -157,6 +157,8 @@ typedef struct OptionsContext {
     int        nb_presets;
     SpecifierOpt *copy_initial_nonkeyframes;
     int        nb_copy_initial_nonkeyframes;
+    SpecifierOpt *copy_prior_start;
+    int        nb_copy_prior_start;
     SpecifierOpt *filters;
     int        nb_filters;
     SpecifierOpt *fix_sub_duration;
@@ -326,6 +328,7 @@ typedef struct OutputStream {
     int stream_copy;
     const char *attachment_filename;
     int copy_initial_nonkeyframes;
+    int copy_prior_start;
 
     int keep_pix_fmt;
 } OutputStream;
diff --git a/ffmpeg_opt.c b/ffmpeg_opt.c
index 3d73564..2c5fbfb 100644
--- a/ffmpeg_opt.c
+++ b/ffmpeg_opt.c
@@ -960,6 +960,9 @@ static OutputStream *new_output_stream(OptionsContext *o, AVFormatContext *oc, e
     ost->max_frames = INT64_MAX;
     MATCH_PER_STREAM_OPT(max_frames, i64, ost->max_frames, oc, st);
 
+    ost->copy_prior_start = -1;
+    MATCH_PER_STREAM_OPT(copy_prior_start, i, ost->copy_prior_start, oc ,st);
+
     MATCH_PER_STREAM_OPT(bitstream_filters, str, bsf, oc, st);
     while (bsf) {
         if (next = strchr(bsf, ','))
@@ -2316,6 +2319,8 @@ const OptionDef options[] = {
         "exit on error", "error" },
     { "copyinkf",       OPT_BOOL | OPT_EXPERT | OPT_SPEC,            { .off = OFFSET(copy_initial_nonkeyframes) },
         "copy initial non-keyframes" },
+    { "copypriorss",    OPT_INT | HAS_ARG | OPT_EXPERT | OPT_SPEC,   { .off = OFFSET(copy_prior_start) },
+        "copy or discard frames before start time" },
     { "frames",         OPT_INT64 | HAS_ARG | OPT_SPEC,              { .off = OFFSET(max_frames) },
         "set the number of frames to record", "number" },
     { "tag",            OPT_STRING | HAS_ARG | OPT_SPEC | OPT_EXPERT,{ .off = OFFSET(codec_tags) },