[FFmpeg-user] Need more detailed description of the behaviour of the "-ac <channelcount>" option

[Christoph Gerstbauer]

Am 02.07.2015 um 11:04 schrieb Paul B Mahol:
> On 7/2/15, Christoph Gerstbauer <christophgerstbauer at gmail.com> wrote:
>>> Then please don't use it, use an audiofilter instead.
>>> (The one that fits your needs.)
>>>
>>> I am not convinced that the current mapping of -ac
>>> to aresample is immutable.
>>> (Even if it is, you can still use the filter and
>>> you are on the safe side.)
>>>
>>> Carl Eugen
>> Hello Carl, so what can I do when my target has more audio channel than
>> the source?
>> For example if I have a file with 2ch stereo and my target is 4ch (with
>> ch3 and ch4 silent) how can i do that? I need to generate silence for
>> the last 2 channels because I dont want to copy ch1ch2 to ch3ch4.
>>
>> If I have a target with less channels than the source I use the
>> -map_channel option:
>> Like: ffmpeg -i "24bitaudio8CH.wav" -acodec pcm_s16le -map_channel 0.1.0
>> -map_channel 0.1.1 -ac 2 "16bitaudio2CH_ch1ch2.wav"
>>
>> So is this possible?:
>> ffmpeg -i "2ch_audio_source.wav" -i "mono-silence" -acodec pcm_s16le
>> -map_channel 0.1.0 -map_channel 0.1.1 -map_channel 1.0.0 -map_channel
>> 1.0.0  "4ch_audio_target.wav"
>> Is there a filter which can generate silence as input source?
> See anullsrc and aevalsrc.

Is anullsrc filter about to be debrecated in some years?
I think anullsrc will be debrecated because aevalsrc offers mor e 
possibilities to generate sound or silence.
And anullsrc only generates silence.

Is this correct?
So would it be better to use aevalsrc (just for generating silence), or 
are there any known bugs at "aevalsrc"?

Best Regards
Christoph

>
>> Best Regards
>> Christoph
>>
>>
>> _______________________________________________
>> ffmpeg-user mailing list
>> ffmpeg-user at ffmpeg.org
>> http://ffmpeg.org/mailman/listinfo/ffmpeg-user
>>
> _______________________________________________
> ffmpeg-user mailing list
> ffmpeg-user at ffmpeg.org
> http://ffmpeg.org/mailman/listinfo/ffmpeg-user