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  #1  
06-09-2017, 03:57 PM
oldsyd oldsyd is offline
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I've been transferring VHS video from a JVC HM-DH40000U using the Firewire interface directly to hard drive. The result is a M2T file that contains MPEG 2 video and then what appears to be MPEG 1 audio and another audio track which is PCM. The video is 480i NTSC 720 X 480 pixels.

I've done some research on this type of container and format and there isn't much info out there even though it doesn't seem too odd for a digital video format of that era?

What I'm having problems figuring out is the following:
  • How to losslessly edit the M2T files (or do they need to be converted first?)
  • What archival format to convert them to.

I've had limited success using AVIDemux, but I don't think that can import the PCM audio which I think is the higher quality of the two. I also think AVIDemux won't allow me to do simple editing without converting first? I'm less concerned about what archival format we end up with as long as it's not generating digital artifacts and it's not something proprietary. MPEG-2 broadcast or DVD maybe since the source is only 480i? The files are straight captures of entire tapes, so I'm not sure if there are timecode markers where the control track drops? If so, that might be handy for finding "chapters".

As far as enhancement, I think I can find most of that info here (like removing head switching) but first I need to learn to walk.

Here's the MediaInfo on the files I'm working with:

General
ID : 1 (0x1)
Complete name : Sample.m2t
Format : MPEG-TS
File size : 24.2 MiB
Duration : 16 s 297 ms
Overall bit rate mode : Constant
Overall bit rate : 12.4 Mb/s
Maximum Overall bit rate : 12.4 Mb/s
Video
ID : 4096 (0x1000)
Menu ID : 1 (0x1)
Format : MPEG Video
Format version : Version 2
Format profile : Main@Main
Format settings, BVOP : Yes
Format settings, Matrix : Custom
Format settings, GOP : M=3, N=15
Format settings, picture structure : Frame
Codec ID : 2
Duration : 16 s 250 ms
Bit rate mode : Constant
Bit rate : 9 550 kb/s
Width : 720 pixels
Height : 480 pixels
Display aspect ratio : 4:3
Frame rate : 29.970 (30000/1001) FPS
Standard : NTSC
Color space : YUV
Chroma subsampling : 4:2:0
Bit depth : 8 bits
Scan type : Interlaced
Scan order : Top Field First
Compression mode : Lossy
Bits/(Pixel*Frame) : 0.922
Time code of first frame : 00:00:05;00
Time code source : Group of pictures header
GOP, Open/Closed : Open
Stream size : 18.3 MiB (76%)
Audio #1
ID : 4098 (0x1002)
Menu ID : 1 (0x1)
Format : MPEG Audio
Format version : Version 1
Format profile : Layer 2
Codec ID : 3
Duration : 16 s 224 ms
Bit rate mode : Constant
Bit rate : 384 kb/s
Channel(s) : 2 channels
Sampling rate : 48.0 kHz
Compression mode : Lossy
Delay relative to video : -172 ms
Stream size : 761 KiB (3%)
Audio #2
ID : 4100 (0x1004)
Menu ID : 1 (0x1)
Format : PCM
Format settings, Endianness : Little
Muxing mode : SMPTE ST 302
Codec ID : 131
Duration : 16 s 249 ms
Bit rate mode : Constant
Bit rate : 1 536 kb/s
Encoded bit rate : 1 920 kb/s
Channel(s) : 2 channels
Sampling rate : 48.0 kHz
Bit depth : 16 bits
Delay relative to video : -220 ms
Stream size : 2.98 MiB (12%)
Menu
ID : 110 (0x6E)
Menu ID : 1 (0x1)
List : 4096 (0x1000) (MPEG Video) / 4098 (0x1002) (MPEG Audio) / 4100 (0x1004) (PCM)
Maximum bit rate : 12440000
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  #2  
06-09-2017, 04:56 PM
msgohan msgohan is offline
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M2T = M2TS = MPEG-2 Transport Stream. It's the same container format used by Blu-ray, but most discs stuff AVC video and lossless audio into that container.

There are some free tools for editing MPEG-2 streams as losslessly as possible. You'd have to do searches, as I dunno what they are myself. Most will only do cuts at the GOP level, or they will re-encode the whole file. Your GOP is 0.5 sec, so if you are happy with having a little slack or over-trimming, GOP editing would be fine.

The best editors will cut at the GOP level, then re-encode only the few frames necessary to perform your frame-accurate edit. Womble and VideoReDo are the most highly rated ($$).

"Enhancing" these files isn't such a good idea, since they are already in a delivery format, not an editing format. You'll have some compounding compression artifacts even if you way overshoot the existing bitrate on your re-encoding.
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06-10-2017, 05:07 AM
sanlyn sanlyn is offline
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Quote:
Originally Posted by oldsyd View Post
As far as enhancement, I think I can find most of that info here (like removing head switching)
Any alteration of the image requires lossy re-encoding. As noted earlier, final delivery formats are lossy inter-frame encodes not designed for alteration. Here's an article that explains why, with somewhat limited information on a few "editing" formats: http://telestreamblog.telestream.net...hen-editing-2/.
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