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Topic: interpretting ripped CD text info (Read 475 times) previous topic - next topic
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interpretting ripped CD text info

Ripped a bunch of CDs back in 2014 using cdparanoia and some other tools I unfortunately don't recall. At time I made vorbis lossy encoding but I want opus now, for quality with smaller file size for my phone.

I archived each CD rip as a single file along with a file called cdinfo.txt that I know was created with some tool at time of rip but I forget.

Anyway would like to reprocess those archived rips into lossy, but like an idiot I did not take any notes on my previous process and don't remember.

The cdinfo.txt file (among other things) has the following:

Code: [Select]
Disc mode is listed as: CD-DA
CD-ROM Track List (1 - 9)
  #: MSF       LSN    Type   Green? Copy? Channels Premphasis?
  1: 00:02:00  000000 audio  false  no    2        yes
  2: 05:22:40  024040 audio  false  no    2        yes
  3: 10:34:20  047420 audio  false  no    2        yes
  4: 15:40:42  070392 audio  false  no    2        yes
  5: 20:24:02  091652 audio  false  no    2        yes
  6: 24:47:50  111425 audio  false  no    2        yes
  7: 28:20:15  127365 audio  false  no    2        yes
  8: 32:00:20  143870 audio  false  no    2        yes
  9: 35:46:55  160855 audio  false  no    2        yes
170: 39:50:60  179160 leadout (401 MB raw, 401 MB formatted)

Looking at the MSF value in #2 and the MSF value in #1 and taking the difference I get 5:20 which is the length of the first track.
Can I assume that the MSF value then specifies the beginning of the track in the CD? e.g. first track starts 2 seconds in?

Can I assume that the AA:BB:CC is Minutes:Seconds:SixtiethOfSeconds ??

What is the LSN ??

This rip is Tom Petty - Southern Accents.

What I am doing with reprocessing is applying the deemph, then EBU R128 loudness normalize (via ffmpeg-normalize) - yes can use tags for that but a lot of players don't respect them. Then resample to 48/16 (ffmpeg-normalize leaves it at 192/16) via sox with dithering. Then split into individual wave files, then lossy encode.

But I need to know how to interpret the MSF and maybe LSN to get sox to split correctly.

I just didn't take notes on what those things mean, given that nothing in the : delimited fields are > 59 I assume they are scale of 60 but I have no idea what the LSN field is.

Thank you to anyone familiar with this format.

Re: interpretting ripped CD text info

Reply #1 –
Okay I found the shell script I used to process it before.
It looks like the last :NN is actually frames where 75 of them are second.

Re: interpretting ripped CD text info

Reply #2 –
Yes, the MSF value specifies the beginning of the track in the CD. It's typical for there to be 2 seconds of lead-in (with no audio) before the first track.

The MSF column is formatted in Minutes:Seconds:Frames, where there are 75 frames per second.

The LSN is the logical sector number. It's the same information as the MSF column, but in terms of frames (1/75th of a second) since the beginning of the audio.
 

Re: interpretting ripped CD text info

Reply #3 –
Got it all working beautifully. All the other CDs I ripped should be pretty easy now. Though my taste in music has changed, don't think I'll bother with a lot of them as I never listen to my existing vorbis for a lot of them ;)
 
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