listening test at 160 kbps
Reply #23 – 2004-06-19 19:04:09
I'm back, with the same test, but at higher setting: -q 6.00...6.50. Samples are the same. I was nevertheless short in time, and I didn't ABXed the last files. For these files, the difference in notation may be imprecise (it means that small differences in notation and hierarchy are maybe unjustifed). For those wondering about setting used for CVS encoder (-q 6,50): I don't have any internet access at home, and I hadn't the correspondant values found by phong when I started the test. I've at first encoded all files with CVS -q 6,22 like aoTuV, but I feared that bitrate was too low. Therefore, I've decided to round the setting to a nice 6,50. It's probably a bit too high, but quality shouldn't really change between the setting I used and the ideal one (6,36 according to phong bitrate table). RESULTS Log files are here (few or even no comments): here CONCLUSIONS • CVS encoder have serious troubles with transients, even at -q 6,50 (210 kbps nominal, which is a pretty high bitrate for a lossy encoder). Something like brightness is also audible with some files, but it's not really annoying, and very far from thickness/coarseness heard previously at -q 5,50, which considerably lowered the notation. In other words, quality progress a lot between -q 5,50 and -q 6,50; pre-echo is in my opinion the biggest problem (but not the only one) of CVS encoders at -q 6...9 settings. • In this conditions, a CVS encoder tweaked for pre-echo should be impressive. And it's the case for GT3b2, which progressed a lot between the two tests (-q 5.00 then -q 6.00). Incidentally, 30% of the samples were transparent on my test (I could probably find more differences with insane concentration). Interesting to note: the sample "Die Schlacht ", symptomatic of the coarseness of vorbis, was here fully transparent on violins with both CVS and GT3b2. Other interesting point: micro-attacks (creaking, Hmong, Pierre Réfléchies, Orion II ) are still better with GT3b2 than with any other vorbis encoder, though extra-noise is still perceptible. • aoTuV's performances are now between CVS and GT3b2. It's always better than CVS (except one case, but it was on quick test, without ABX: notation is a bit imprecise, and hierarchy might be wrong). But it's rarely better or simply eaqual than GT3b2. On very sharp attacks (castanets...), aoTuV performances are a bit disapointing. We could expect more from a modern lossy encoders. On moderately sharp attacks, pre-echo is limited, not really annoying. We could also note that the progress between the notation on the two tests is small. aoTuV -q 6,22 is just slightly better than -q 5,50, whereas progress with CVS and GT3b2 is very impressive. It's not a real problem, quite the reverse: it proves that aoTuV quality is more linear than CVS/GT3, without huge frontier between - q 5,99 and -q 6,00. Last thing: when brightness is audible with CVS/GT3, aoTuV hasn't problem, or lowers it (cf. Atem-Lied for a good exemple). • In conclusion, aoTuV needs more tuning in order to be •fully• recommanded over GT3b2. A temporary solution might be something like an aoTuV+GT3 encoder. Ready for another round?