AAC at 128kbps test - FINISHED
AAC at 128kbps test - FINISHED
Jun 16 2003, 08:12
Joined: 30-September 01
Member No.: 81
I'd like to announce that my first listening test successfuly ended.
The results page is available here:
(veteran forum members will notice that page resembles to someone else's)
So far, you only get results for each sample, and overall results.
Tomorrow, I'll add fancy things like user comments, bitrates, etc.
If someone notices flaws or typos, please report in this thread or through PM. Thanks a lot.
(Also, info on the 41_30sec sample is welcome)
For those really hurried, here is the overall plot:
Once again, thanks to everyone that participated. Hopefully, there'll be more in a month.
Get up-to-date binaries of Lame, AAC, Vorbis and much more at RareWares:
Jun 16 2003, 12:08
ABC/HR developer, ff123.net admin
Group: Developer (Donating)
Joined: 24-September 01
Member No.: 12
Nice test, Roberto.
A few comments:
1. I think classical and jazz could have been better represented.
2. It should be noted somewhere, probably in the recommendations section, that this was a CBR test only, and that Nero and Psytel also have VBR modes, which perform better, according to Guruboolez. You might link to his listening results.
3. The crack about people advertising for FAAC is unneccessary. and doesn't help you win over a certain enthusiast to participate in your next test.
4. You mention that you used an ANOVA analysis, but maybe you should also mention that this is different from what the 64 kbit/s test used. The similar presentation format might make people think that all the analysis was identical. The difference is mainly one about risk. The ANOVA / Fisher LSD method is more at risk for falsely identifying differences between codecs. On the other hand, it's more sensitive than the Tukey HSD.
5. I'm still uncomfortable with the squishy way that a summary graph is constructed. But since I can't think of a better way, and people have a need to see things in one, concise picture, I suppose it must be that way.
6. In the more detailed pages to follow, I'd like to see some mention about how a time misalignment of only 25 msec spoiled at least one result. Also, I'd like to see some mention of the results you threw out for rating the original less than 5.
Some ideas for a future test:
1. Perhaps another call for samples -- classical and jazz samples -- would be profitable.
2. You might think about adding at least one anchor sample -- a lowpassed version of the original, a la MUSHRA. This can be done with a small filesize penalty using Sox. That would help to keep the ratings in perspective.
3. Verifying VBR average bitrates: I think that this task could be split up among several people, each encoding whole albums with all codecs.
Edit: Oh, and if iTunes doesn't use the same codec that you used for this test, I would make some mention of that fact too.
Edit2: The next test you'll probably want to be sure to check for level (volume) differences too.
This post has been edited by ff123: Jun 16 2003, 12:14
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