On 22.06.2015 09:55, Petter Reinholdtsen wrote:
[Peter Belkner]
I was testing with Winamp and the FFmpeg based "in_ffsox" input plugin.
It was not "stuttering" at all. I discovered "stuttering" only when
testing with VLC player.
Aha.
Meanwhile I've learned that we have two issues:
1. "20030213-cvs.mpeg" had not processed at all (i.e. just loudness
analysis was aborting with an error and hence it could not have
"stuttered")
2. "DavidGallo_2007.dv" stutters.
Aha. That is strange, as I am quite sure I tested it before reporting
the bug. Anyway, I trust your observations and must remember
incorrectly.
The (previous) patch solves the first issue. The idea is to throw away
packages FFmpeg cannot deal with.
Given that it only happen once, I guess the package is at the start or
at the end. Perhaps the message should be extended to mention how far
into the stream the package is dropped.
The FFmpeg example "ffmpeg/doc/examples/decoding_encoding.c" aborts in
such a case:
len = avcodec_decode_audio4(c, decoded_frame, &got_frame, &avpkt);
if (len < 0) {
fprintf(stderr, "Error while decoding\n");
exit(1);
}
On the other hand the FFmpeg program silently deals with the file.
I don't think that it is a good idea to let BS1770GAIN re-implemet large
portions of FFmpeg.
Maybe we should revert to the original behavior of aborting in case
avcodec_decode_audio4() fails and make it in option to continue in case
of an error. It's then up to the user to see whether it makes sense.
Am I right in believing that many such dropped packages in the middle of
the stream will cause audio and video to get out of sync?
The following patch solves "stuttering" (but really is some kind of a
"sledgehammer")
diff -rc ./bs1770gain-0.4.4-beta2/libffsox-2/ffsox_frame_writer.c
./bs1770gain-0.4.4-beta3/libffsox-2/ffsox_frame_writer.c
*** ./bs1770gain-0.4.4-beta2/libffsox-2/ffsox_frame_writer.c
2015-06-14 18:11:19.000000000 +0200
--- ./bs1770gain-0.4.4-beta3/libffsox-2/ffsox_frame_writer.c
2015-06-22 09:12:36.000000000 +0200
***************
*** 145,150 ****
--- 145,154 ----
if (0!=*got_packet) {
av_packet_rescale_ts(pkt,cc->time_base,st->time_base);
+ // where do the "magic" factor 0.5 come from?
+ pkt->dts>>=1;
+ pkt->pts>>=1;
+ pkt->duration>>=1;
if (ffsox_stream_interleaved_write(so,pkt)<0) {
DMESSAGE("writing packet");
Maybe Carl Eugen can provide some insight into how to align the time
scales between streams.
I tested and this solve the stuttering for me too, but I have no idea
about the mathematics involved here.
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