[FFmpeg-trac] #10345(undetermined:reopened): New filter for de-Multiplexing recorded mono audio

[FFmpeg]

#10345: New filter for de-Multiplexing recorded mono audio
-------------------------------------+-------------------------------------
             Reporter:  Noitarud     |                    Owner:  (none)
                 Type:  enhancement  |                   Status:  reopened
             Priority:  normal       |                Component:
                                     |  undetermined
              Version:  unspecified  |               Resolution:
             Keywords:  Multiplex    |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
Description changed by Noitarud:

Old description:

> Hello all I would like to tell of a discovery I made over ten years ago,
> it might have some novelty or serious use as a filter or even a codec.
>
> I built a mono FM transmitter and once when I tested it I had nothing to
> transmit so I used an FM radio station, I received it on another radio –
> and the STEREO light came on!
>
> Would you like to create a filter, since this would also work with mono
> VHS taped recordings of television:
> •Decode mono-multiplex to stereo
> •subtitles may also be acquirable (FM? I do not have info for stereo,
> only quad (see Comment 6), FM radio should have some embedded things. For
> TV, they are probably using teletext, which could become another FFMPEG
> filter idea).
>
> Cons:
> •I do not think Quad is in active use (despite modern cars being equipped
> with four speakers), so decode to quad is not necessary.
> •niche, and people may assume if acquired in mono there is no way you
> could get stereo.
> •TV stereo may be implemented different to FM stereo, I have not yet
> tested Stereo TV modulators.
> •have not tested with VHS recordings or audio cassette to see if
> retained.
> •analog TV is outdated
>

> (The rest is not related to ffmpeg, but would be useful elsewhere)
>
> {{{
> For these two functions,
> •Encode stereo to mono-multiplex
> •Encode quadrophonic to mono-multiplex
> Better to create an output filter (like WaveOut) or as FFDSHOW filter, so
> all MP3s and such can be played without file conversion.
>
> And consider a codec, the monaural stream could confer benefits, and for
> the stream's decoder, have either full decode [or decode to mono-
> multiplex (for stereo or quadrophonic FM receivers) - not required if can
> Encode output sound, may assist troubleshooting].
> }}}

New description:

 Hello all I would like to tell of a discovery I made over ten years ago,
 it might have some novelty or serious use as a filter or even a codec.

 I built a mono FM transmitter and once when I tested it I had nothing to
 transmit so I used an FM radio station, I received it on another radio –
 and the STEREO light came on!

 Would you like to create a filter, since this would also work with mono
 VHS taped recordings of television:
 •Decode mono-multiplex to stereo
 •Subtitles may also be acquirable (FM? I do not have info for stereo, only
 quad (see Comment 6), FM radio should have some embedded things. For TV,
 they are probably using teletext, which could become another FFMPEG filter
 idea, again a novelty, but part of the stream).

 Cons:
 •I do not think Quad is in active use (despite modern cars being equipped
 with four speakers), so decode to quad is not necessary.
 •Niche, and people may assume if acquired in mono there is no way you
 could get stereo.
 •TV stereo may be implemented different to FM stereo, I have not yet
 tested Stereo TV modulators.
 •I have not tested with VHS recordings or audio cassette to see if
 actually usable.
 •Analog TV is outdated


 (The rest is not related to ffmpeg, but would be useful elsewhere)

 {{{
 For these two functions (for retransmission to mono transmitter)
 •Encode stereo to mono-multiplex
 •Encode quadrophonic to mono-multiplex
 Better to create an output filter (like WaveOut) or as FFDSHOW filter, so
 all MP3s and such can be played without file conversion.

 And consider a codec, the monaural stream could confer benefits, and for
 the stream's decoder, have either full decode [or decode to mono-multiplex
 (for stereo or quadrophonic FM receivers) - not required if can Encode
 output sound, may assist troubleshooting].
 }}}

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Ticket URL: <https://trac.ffmpeg.org/ticket/10345#comment:11>
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