[Cin] HDV is really 4 channel?
Terje J. Hanssen
terjejhanssen at gmail.com
Mon Jan 29 14:04:39 CET 2024
Den 17.01.2024 00:54, skrev Andrew Randrianasulu:
>
>
> 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
>> <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.
>> =====
>>
>>
To supplement the earlier information with wikipedia's hdv audio
specification:
https://en.wikipedia.org/wiki/HDV#Specifications
Audio
Compression MPEG-1 Audio Layer II, PCM (HDV 720p)
MPEG-1 Audio Layer II (HDV 1080i)
Sampling frequency 48 kHz
Quantization 16 bits
Audio modes and data rate
MPEG-1 Part 3 AL 2 Stereo (2-channel) at 384 kbit/s (192 kbit/s per
channel);
optional MPEG-2 Part 3 AL 2 4-channel at 96 kbit/s per channel.
>>
>> 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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