[FFmpeg-user] Stereo AAC

[Marcin W.]

Because you three times specify -map 0:1. Check stream.mapping.

wt., 17 kwi 2018, 05:45 użytkownik antony baxter <antony.baxter at gmail.com>
napisał:

> Hi all,
>
> I have some video files with a DTS audio stream. I'm trying to add a
> couple of additional audio streams into the file, transcoded from the
> DTS stream. My command line is:
>
>    ffmpeg
>       -i "${input}"
>       -map 0:0
>       -map 0:1
>       -map 0:1
>       -map 0:1
>       -c:v copy
>       -movflags +faststart
>       -c:a:0 aac
>       -b:a:0 192k
>       -ac 2
>       -metadata:s:a:0 title="AAC Stereo Audio"
>       -c:a:1 ac3
>       -ac 6
>       -metadata:s:a:1 title="AC3 5.1 Audio"
>       -c:a:2 copy
>       -disposition:a -default
>       -disposition:a:0 default
>       -f mp4
>       "${output}.mp4"
>
> However, this isn't doing exactly what I expected. The output is:
>
> Output #0, mp4, to 'output.mp4':
>   Metadata:
>     Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661),
> yuv420p(progressive), 1920x1036 [SAR 1:1 DAR 480:259], q=2-31, 23.98
> fps, 23.98 tbr, 16k tbn, 1k tbc (default)
>     Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz,
> 5.1, fltp, 192 kb/s (default)
>     Metadata:
>       title           : AAC Stereo Audio
>     Stream #0:2(eng): Audio: ac3 (ac-3 / 0x332D6361), 48000 Hz, 5.1,
> fltp, 448 kb/s
>     Metadata:
>       title           : AC3 5.1 Audio
>     Stream #0:3(eng): Audio: dts (DTS) (mp4a / 0x6134706D), 48000 Hz,
> 5.1(side), fltp, 1536 kb/s
>
> Note that Stream #0:1 is being output as AAC 5.1 instead of AAC stereo.
>
> How come the -ac 2 flag is being ignored - do I need to specify which
> stream this applies to, and if so how?
>
> Thank you all
>
> Ant.
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