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

[Paul B Mahol]

Also note that still channel layouts in FFmpeg do not store/signal anywhere
real channel horizontal/vertical angle.

On Wed, Jan 29, 2025 at 4:46 PM Paul B Mahol <onemda at gmail.com> wrote:

> 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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>>
>