[Cin] HDV is really 4 channel?

Wed Jan 17 00:54:15 CET 2024

ср, 17 янв. 2024 г., 02:07 Terje J. Hanssen <terjejhanssen at gmail.com>:

>
>
> Den 16.01.2024 23:32, skrev Andrew Randrianasulu:
>
>
>
> ср, 17 янв. 2024 г., 01:14 Andrew Randrianasulu <randrianasulu at gmail.com>:
>
>>
>>
>> ср, 17 янв. 2024 г., 01:04 Andrew Randrianasulu <randrianasulu at gmail.com
>> >:
>>
>>>
>>>
>>> ср, 17 янв. 2024 г., 00:42 Terje J. Hanssen <terjejhanssen at gmail.com>:
>>>
>>>>
>>>>
>>>> Den 16.01.2024 21:35, skrev Andrew Randrianasulu:
>>>>
>>>>
>>>>
>>>> вт, 16 янв. 2024 г., 23:30 Terje J. Hanssen <terjejhanssen at gmail.com>:
>>>>
>>>>>
>>>>>
>>>>> 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.)
>>>>
>>>>
>>> yeah, seems to be rarely supported on HDV cameras, see
>>>
>>> https://forum.blackmagicdesign.com/viewtopic.php?f=33&t=171688
>>>
>>> but still!
>>>
>>
>>
>> https://ieba.wordpress.com/2008/01/21/hdv-grows-up-sonys-hvr-s270-and-hvr-z7/
>>
>> =====
>> *4-Channel Audio*
>> The HDV specification, like the DV specification, has allowed for
>> four-channel audio recording from the outset. Few cameras took advantage of
>> it, and when they did, it was an add-on that did not maintain full balanced
>> audio throughout. Though the smaller Sony HVR-Z7 records only two channels
>> of audio, the larger HVR-S270 has two XLR inputs in the front of the
>> camcorder and two XLR inputs on the back of the camcorder. Each one has a
>> separate audio level control and an automatic level control switch on the
>> side of the camcorder.
>> =====
>>
>
>
> and samples:
>
> https://forum.doom9.org/archive/index.php/t-125966-p-46.html
>
> =====
>
> As you can see 4 channel audio is part of the HDV format. I am not sure if
> there are actually 2 audiostreams or only 1. There is no way I can check
> this because the camera itself only outputs the 4 ch and no 2 ch. But the
> computer will only play a 2 ch. But when you compare the MediaInfo audio
> information with the specs I expect that there are 2 audio stream just like
> eac3to detects. It would be very very nice if HDV support can be integrated
> into eac3to because many professional cameramen are looking for an solution.
>
> Currently eac3to extracts the m2v and 2ch audio stream fine. Only the 4
> channel stream isn't detected nor extracted. I uploaded 2 sample to my
> server for analysis:
> http://tools.twanwintjes.nl/uploads/temp/00_0001_2010-11-07_153401.M2T
> (49 seconds / 152MB) - Right Click --> Save As
> http://tools.twanwintjes.nl/uploads/temp/00_0002_2010-11-07_214302.M2T
> (44 seconds / 137MB) - Right Click --> Save As
>
>
> ====
>
> yes, files still there :)
>
> Yeah, I saw some of the forum threads and had a look on the sample files.
> For me they the ffprobe outputs were identical with my own hdv.m2t files.
> I think as Mullen wrote, the limit for miniDV or HDV tapes was utilized
> for 1080i HD2 with 25 Mbps.
> Only the 720p HD2 format with 19 Mbps had PCM tracs free for later use.
> Maybe other camcorders..
>

=====

>
.2.1.8 Adaptive Multichannel Prediction
Adaptive multichannel prediction is used to reduce the inter-channel
redundancy. When using multichannel
prediction, the signals in the transmission channels T2..T4 are predicted
from the signals in the MPEG-1 compatible
part of the bit stream (Lo, Ro). Instead of the actual signals in a subband
group, the prediction error is transmitted,
together with predictor coefficients and delay compensation.
=======

from

https://courses.e-ce.uth.gr/CE401/tree_menu/tutorials/MPEG2/13818-3.pdf


> Possibly file storage on other disc media could be utilized for larger
> bandwidth.
> But I cannot see it was mentioned for the targeted camcorder disc recorder
>
> https://www.bhphotovideo.com/c/product/461819-REG/Sony_HVRDR60_HVRDR60_Hard_Disk_Recording.html
>
>
>>
>>
>>>
>>>
>>>>
>>>>
>>>> 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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