avconv: distinguish between -ss 0 and -ss not being used

Using -ss 0 to drop frames with negative timestamps is a perfectly valid
use case.

1 files changed, 5 insertions, 3 deletions

diff --git a/avconv_opt.c b/avconv_opt.c
index f96feced9a..c8d917638b 100644
--- a/avconv_opt.c
+++ b/avconv_opt.c
@@ -113,6 +113,7 @@ static void init_options(OptionsContext *o)
     memset(o, 0, sizeof(*o));
 
     o->mux_max_delay  = 0.7;
+    o->start_time     = AV_NOPTS_VALUE;
     o->recording_time = INT64_MAX;
     o->limit_filesize = UINT64_MAX;
     o->chapters_input_file = INT_MAX;
@@ -658,13 +659,13 @@ static int open_input_file(OptionsContext *o, const char *filename)
         exit_program(1);
     }
 
-    timestamp = o->start_time;
+    timestamp = (o->start_time == AV_NOPTS_VALUE) ? 0 : o->start_time;
     /* add the stream start time */
     if (ic->start_time != AV_NOPTS_VALUE)
         timestamp += ic->start_time;
 
     /* if seeking requested, we execute it */
-    if (o->start_time != 0) {
+    if (o->start_time != AV_NOPTS_VALUE) {
         ret = av_seek_frame(ic, -1, timestamp, AVSEEK_FLAG_BACKWARD);
         if (ret < 0) {
             av_log(NULL, AV_LOG_WARNING, "%s: could not seek to position %0.3f\n",
@@ -1212,7 +1213,8 @@ static int copy_chapters(InputFile *ifile, OutputFile *ofile, int copy_metadata)
 
     for (i = 0; i < is->nb_chapters; i++) {
         AVChapter *in_ch = is->chapters[i], *out_ch;
-        int64_t ts_off   = av_rescale_q(ofile->start_time - ifile->ts_offset,
+        int64_t start_time = (ofile->start_time == AV_NOPTS_VALUE) ? 0 : ofile->start_time;
+        int64_t ts_off   = av_rescale_q(start_time - ifile->ts_offset,
                                        AV_TIME_BASE_Q, in_ch->time_base);
         int64_t rt       = (ofile->recording_time == INT64_MAX) ? INT64_MAX :
                            av_rescale_q(ofile->recording_time, AV_TIME_BASE_Q, in_ch->time_base);