IPB

Welcome Guest ( Log In | Register )

LAME Q Switch
Makaki
post Jun 1 2013, 00:21
Post #1





Group: Members
Posts: 62
Joined: 20-May 13
Member No.: 108227



Out of curiosity, I was looking for all the information that I could find on LAME's Q switch when using CBR. Other than:
-q 0: Highest quality, very slow
-q 9: Poor quality, but fast

I wanted to know a little more of what was happening with each setting (without having to go into the source code myself). So I used the verbose flag, and then compared the output and encoding times. I did a few tests and decided to post the results here in case someone else was curious too. All tests where done with -b 320 (CBR 320). If someone has more insight, any information would be welcome.

differences with previous level
observations

-q 0
  • huffman search: best (outside loop)
  • subblock gain: 1
  • noise shaping: 1
  • ^ amplification: 2
  • ^ stopping: 1

-q 1 same output, but faster (unknown difference)
  • huffman search: best (outside loop)
  • subblock gain: 1
  • noise shaping: 1
  • ^ amplification: 2
  • ^ stopping: 1

-q 2
  • huffman search: best (outside loop)
  • subblock gain: 1
  • noise shaping: 1
  • ^ amplification: 1
  • ^ stopping: 1

-q 3 same output, but faster (unknown difference)
  • huffman search: best (outside loop)
  • subblock gain: 1
  • noise shaping: 1
  • ^ amplification: 1
  • ^ stopping: 1

-q 4
  • huffman search: best (outside loop)
  • subblock gain: 1
  • noise shaping: 1
  • ^ amplification: 0
  • ^ stopping: 0

-q 5
-q 6
  • huffman search: normal
  • subblock gain: 1
  • noise shaping: 1
  • ^ amplification: 0
  • ^ stopping: 0

-q 7
-q 8
-q 9
  • huffman search: normal
  • subblock gain: -1
  • noise shaping: 0
  • ^ amplification: 0
  • ^ stopping: 0


NOTE: 5-6 seem identical, Same for 7-9.
Go to the top of the page
+Quote Post

Posts in this topic
- Makaki   LAME Q Switch   Jun 1 2013, 00:21
- - lvqcl   You can also look at lame_init_qval() function her...   Jun 1 2013, 00:32
- - db1989   Thanks for the pointer. Well, I’ll take the ...   Jun 1 2013, 01:06
|- - BFG   Interesting info (even though I lack technical exp...   Jun 1 2013, 02:14
- - Makaki   The code seems kind of clear, after someone points...   Jun 1 2013, 02:45
- - db1989   QUOTE (BFG @ Jun 1 2013, 02:14) Interesti...   Jun 1 2013, 14:50
- - db1989   OK, here we are. I performed bit-comparisons of di...   Jun 1 2013, 15:21
- - robert   The current (new) VBR mode uses different code pat...   Jun 1 2013, 17:34
- - Makaki   I didn't want to compare the output files them...   Jun 1 2013, 21:16
- - db1989   robert: Thanks very much for the info! Can we...   Jun 1 2013, 22:54
|- - robert   QUOTE (db1989 @ Jun 1 2013, 23:54) Also, ...   Jun 2 2013, 19:00
- - db1989   Sorry, my mistake: it should be full_outer_loop. W...   Jun 2 2013, 19:18
- - robert   Well, verbose doesn't print everything thinkab...   Jun 2 2013, 19:41
- - db1989   Thanks for the info, and sorry for the confusion. ...   Jun 2 2013, 19:45
- - Makaki   Do we agree the HTML documentation could use an up...   Jun 2 2013, 20:06
|- - db1989   Certainly it requires updating to reflect the thre...   Jun 2 2013, 23:46
- - Makaki   Work in progress: http://wiki.hydrogenaudio.org/i...   Jun 3 2013, 14:56
- - db1989   I held off from saying it for the title of this th...   Jun 3 2013, 16:27
- - Makaki   Since it's a work in progress, I could create ...   Jun 3 2013, 16:40
|- - db1989   QUOTE (Makaki @ Jun 3 2013, 16:40) No adm...   Jun 3 2013, 16:52
- - Makaki   With the information I have so far, which would ne...   Jun 3 2013, 16:56
- - db1989   See my edits, now at http://wiki.hydrogenaudio.org...   Jun 3 2013, 17:22
- - lvqcl   AFAIK previously -q 5 was the default for CBR/ABR,...   Jun 3 2013, 17:36
- - Makaki   QUOTE (db1989 @ Jun 3 2013, 12:22) Where ...   Jun 3 2013, 17:40
- - Makaki   In order for me to update my "latest" su...   Jun 3 2013, 18:12
- - [JAZ]   Makaki: The most up-to-date information is here: h...   Jun 3 2013, 19:31
- - db1989   The official documentation, even the latest, defin...   Jun 3 2013, 22:23


Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 



RSS Lo-Fi Version Time is now: 30th August 2014 - 06:45