[libav-tools] AVI(ac3): Broken sound after copy

Mathieu Malaterre mathieu.malaterre at gmail.com
Sat Apr 4 15:23:26 CEST 2015


Hi,

I am trying to understand why avconv is breaking sound on a working
AVI input. I can play a video on my FreeBox V5 just fine. However
after copy:

$ avconv -i input.avi -codec copy output.avi

The generated `output.avi` appears as non working on my FreeBox V5
player. If I compare (avprobe -show_streams) here is what I see:

$ avprobe -show_streams input.avi > /tmp/1
$ avprobe -show_streams output.avi > /tmp/2
$ diff -u /tmp/1 /tmp/2
--- /tmp/1 2015-04-04 15:13:53.222288651 +0200
+++ /tmp/2 2015-04-04 15:19:19.898275904 +0200
@@ -26,15 +26,15 @@
 codec_long_name=ATSC A/52A (AC-3)
 codec_type=audio
 codec_time_base=1/48000
-codec_tag_string=[0] [0][0]
-codec_tag=0x2000
+codec_tag_string=[254][255][0][0]
+codec_tag=0xfffe
 sample_rate=48000.000000
 channels=6
 bits_per_sample=0
 r_frame_rate=0/0
-avg_frame_rate=125/4
-time_base=1/56000
+avg_frame_rate=0/0
+time_base=4/125
 start_time=0.000000
 duration=N/A
-nb_frames=127391040
+nb_frames=33174
 [/STREAM]

Does the `codec_tag_string` value have any influence here ? The video
plays just fine, so I assumed I can simply discard the warning
message:

[avi @ 0x8a5460] non-interleaved AVI
[mpeg4 @ 0x8a76e0] Invalid and inefficient vfw-avi packed B frames detected

Thanks for suggestions,


More information about the libav-tools mailing list