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

Luca Barbato lu_zero at gentoo.org
Sat Apr 4 18:48:16 CEST 2015


On 04/04/15 15:23, Mathieu Malaterre wrote:
> 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 ?

I think so, if you add -tag:a 0x2000 does it work?

lu



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