fftools/ffmpeg: stop using OutputStream.frame_number for streamcopy

This field is currently used by checks
- skipping packets before the first keyframe
- skipping packets before start time
to test whether any packets have been output already. But since
frame_number is incremented after the bitstream filters are applied
(which may involve delay), this use is incorrect. The keyframe check
works around this by adding an extra flag, the start-time check does
not.

Simplify both checks by replacing the seen_kf flag with a flag tracking
whether any packets have been output by do_streamcopy().

1 files changed, 1 insertions, 1 deletions

diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
index 1e14bf9fa9..04369df139 100644
--- a/fftools/ffmpeg.h
+++ b/fftools/ffmpeg.h
@@ -536,7 +536,7 @@ typedef struct OutputStream {
     int inputs_done;
 
     const char *attachment_filename;
-    int seen_kf;
+    int streamcopy_started;
     int copy_initial_nonkeyframes;
     int copy_prior_start;
     char *disposition;