[FFmpeg-user] Command line to show channel label/position

[Paul B Mahol]

For your specific case, one would need to look at flac specification, and
check does ffmpeg follow specification correctly.

On Wed, Jan 29, 2025 at 10:24 AM MrNice <wxcvbn2006 at iol.ie> wrote:

> >> On Jan 28, 2025, at 4:14 PM, MrNice <wxcvbn2006 at iol.ie> wrote:
> >>
> >> On 28/01/2025 18:26, Carl Zwanzig wrote:
> >>> On 1/28/2025 8:18 AM, MrNice wrote:
> >>>> have an audio file, with MediaInfo I get
> >>>> Audio
> >>>> Channel layout                           : L R Ls Rs
> >>>>   > ffmpeg -v error -layouts | awk '/quad /{print $2}'
> >>>> FL+FR+BL+BR
> >>>> What is the correct answer?
> >>> Both.
> >>> Left, assumed to be front (L) = Front Left (FL)
> >>> Left surround/side (Ls) = Back Left (BL)
> >>> etc
> >>>
> >>> (that's part way down the AudioChannelManipulation page, even farther
> down is a list of the channel names and standard layouts, also in the
> -layouts output)
> >>>
> >>> z!
> >>>
> >>> _______________________________________________
> >> Are you sure for good Carl?
> >>
> >> AFAIK, LS is surround and BL is back/Rear
> >>
> >> Please look here
> >>
> >> https://mediaarea.net/AudioChannelLayout
> >>
> >> They say, depending of standardization;
> >> Left Surround = Ls = CL = SL = Ls (MediaInfo name)
> >> Right Surround = Rs = CR = SR = Rs (MediaInfo name)
> >> Left Rear Surround = Lrs = BL = Lsr = SL = Lb (MediaInfo name)
> >> Right Rear Surround = Rrs = BR = Rsr = Rb (MediaInfo name)
> >>
> > I'm not sure I understand the question, but I believe that "back"
> channels are only involved if there are more than 5 distinct audio signals
> plus one low frequency signal. By way of explanation, I believe that 5
> distinct audio signals plus one low frequency signal is the configuration
> commonly referred to as "5.1" audio (front left, front right, center, side
> left, side right, and low frequency). I don't believe that the term "5.1"
> when used to describe an audio standard (summarized as the description of
> speaker locations listed in my previous sentence) specifies any "back'
> audio signals at all. If you wish to convert 5.1 audio to an audio format
> having more distinct signals or sends, then I think it is up to you to
> determine how you would like to distribute the audio signals to make use of
> the additional available channels. Did I say anything useful, or have I
> just confused the issue?
> >
> > LL
> >
> > _______________________________________________
>
> Thank you for your answer.
>
> The point is that ffmpeg and MediaInfo do not output the same answer for
> the channels positions. Side is not Back particularly in the last
> century with quadrophonic.
>
> Or the information embedded in the file is confusing or one of the two
> programs decipher the embedded info in a wrong way. It could be
> interesting to know what is effectively coded inside the file and as
> well how the 2 programs decipher and output that data to understand the
> difference.
>
> Moreover, to get an accurate knowledge on ffmpeg, it could be
> interesting to copy the table https://mediaarea.net/AudioChannelLayout
> in the ffmpeg documentation and add one column with the corresponding
> ffmpeg output.
>
> MrNice
>
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