[Cin] HDV is really 4 channel?

[Terje J. Hanssen]

Den 16.01.2024 21:35, skrev Andrew Randrianasulu:
>
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> вт, 16 янв. 2024 г., 23:30 Terje J. Hanssen <terjejhanssen at gmail.com>:
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>
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>     Den 16.01.2024 20:23, skrev Andrew Randrianasulu:
>>     https://trac.ffmpeg.org/ticket/1258
>>
>>     see attached to this ticket  modded decoder ...
>>
>>     I wonder if Terje's audio really 4ch? if so,may be we can decode
>>     it to 4* wav first, then encode them correctly to bluray lpcm /
>>     dvd pcm / ac3 ...
>
>
>     I did leave out some "empty channels" to simplify and clean up the
>     post. Here are the full ffprobe output for the HDV source
>     (mediainfo was complete):
>
>
>
> well, this ticket still open, so ffmpeg tools do not know yet about 
> this .. extension? It decodes in compat stereo mode. I attached fixed 
> decoder to this ticket, it will be interesting if you just run ffmpeg 
> acodec copy command and then compile and run decoder on it .. it may 
> decode to 4 files! But not sure how it all was arranged when it comes 
> to microphones ...? Does camera contain 4 of them? or you were 
> supposed to connect your own array?

Well, I think Steve Mullen's handbook for Sony FX7 (mine) and V1 clarify 
there is only two audo channels on my FX7::

  * There is two types of HDV: HD1/720p (19 Mbps) and HD2/1080i /25
    Mbps) and Canon's 1080p24.
  * HD1 is recorded to DV tape using only the DV video segment. The PCM
    audio segment is open for future use.
  * HD2 is recorded to DV tape using both the DV video segment and the
    PCM audio segment. A small Subcode (ITI) segment holds data such
  * as timecode. Because no PCM audio segments are available, HD2 cannot
    carry record PCM audio.
  * MPEG-1 Audio:
  * Both HD1 and HD2 support two audio channels of audio signals that
    are digitized with a 48kHz at 16-bit quantization and compressed to
  * 384kbps by MPEG-1 Audio Layer 2 encoding. ProHD adds two-channel PCM
    audio thus creating a format that can carry four independent
  * channels of audio. (See Chapter 2 for an in-depth introduction to
    MPEG-1 audio.)


>         ffprobe -hide_banner hdv07_05.m2t
>         [mpeg2video @ 0x55d58a968340] Invalid frame dimensions 0x0.
>             Last message repeated 7 times
>         [mpegts @ 0x55d58a93e580] Could not find codec parameters for
>         stream 2 (Unknown: none ([160][0][0][0] / 0x00A0)): unknown codec
>         Consider increasing the value for the 'analyzeduration' (0)
>         and 'probesize' (5000000) options
>         [mpegts @ 0x55d58a93e580] Could not find codec parameters for
>         stream 3 (Unknown: none ([161][0][0][0] / 0x00A1)): unknown codec
>         Consider increasing the value for the 'analyzeduration' (0)
>         and 'probesize' (5000000) options
>         Input #0, mpegts, from 'hdv07_05.m2t':
>         Duration: 00:06:58.27, start: 3276.528000, bitrate: 25626 kb/s
>           Program 100
>           Stream #0:0[0x810]: Video: mpeg2video (Main) ([2][0][0][0] /
>         0x0002), yuv420p(tv, bt709, top first), 1440x1080 [SAR 4:3 DAR
>         16:9], 25000 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
>             Side data:
>         cpb: bitrate max/min/avg: 25000000/0/0 buffer size: 7340032
>         vbv_delay: N/A
>           Stream #0:1[0x814]: Audio: mp2 ([3][0][0][0] / 0x0003),
>         48000 Hz, stereo, fltp, 384 kb/s
>           Stream #0:2[0x815]: Unknown: none ([160][0][0][0] / 0x00A0)
>           Stream #0:3[0x811]: Unknown: none ([161][0][0][0] / 0x00A1)
>         Unsupported codec with id 0 for input stream 2
>         Unsupported codec with id 0 for input stream 3
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