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

[Paul B Mahol]

Search for "surround" left/channel back. To me it looks the flac decoder is
correct.

https://datatracker.ietf.org/doc/rfc9639/

On Wed, Jan 29, 2025 at 4:37 PM MrNice <wxcvbn2006 at iol.ie> wrote:

>
> On 29/01/2025 11:26, Paul B Mahol wrote:
> > 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
> >>
> >> _______________________________________________
> >> ffmpeg-user mailing list
> >> ffmpeg-user at ffmpeg.org
> >> https://ffmpeg.org/mailman/listinfo/ffmpeg-user
> >>
> >> To unsubscribe, visit link above, or email
> >> ffmpeg-user-request at ffmpeg.org with subject "unsubscribe".
> >>
> > _______________________________________________
>
> Unfortunately, I am not skilled enough in that matter to go this way.
>
> Is there de developer who could complete the table
>
> https://mediaarea.net/AudioChannelLayout
>
> With the ffmpeg/ffprobe output ?
>
>
>
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