"satter" Quantizer bei AVC (Transparenz-Qualität)

Sorry, aber mir ist leider nicht klar was Du unter 'maximale Sättigung' verstehst, vermutlich weil der minimale Quantizer bei MPEG-4 ASP nicht 2 sondern ein ist und somit eine maximale Detailerhaltung bei Quantizer 1 stattfindet. (Custom Quantizer Matrizen usw. mal außen vorgelassen)

Cu Selur

Hallo,

vergleichbare Quantizer kannst Du mit dieser Formel berechnen:

H.264QP= 12 + 6*log2(MPEGQP)

Da log2(2) = 1 kommt man auf 18.

Gruß

akapuma

Soweit ich mich erinnere, liegt die "Transparenz" (dass man die Kopie gefühlt kaum noch vom Original unterscheiden kann) etwa bei Quantisierungsfaktoren um 18..20 bei AVC.

...

Okay, wissenschaftlich geht's auch. Aber Logarithmen sind nicht jedermanns Alltagsthema.

Zitat von LigH

Aber Logarithmen sind nicht jedermanns Alltagsthema.

Gerade nicht log2. So geht's:

log2(x) = log(x)/log(2)

Gruß

akapuma

Zitat

Ich meine, dass Quantizer 2 bei ASP das beste Grösse/Qualität Verhältnis hat.

Kann irgendwer diese Aussage mit Daten besättigen? Persönlich hätte ich das beste Qualität/Größe Verhältnis bei wesentlich niedrigeren Quantizern erwartet.

Kleiner Test:
-----------------------------------------------------------------------------------------------------------
Je nach Encode ist der Quantizer anders aber sonst wurden diese Settigs verwendet:

x264 --qp 21 --level 5.1 --ref 16 --keyint 500 --min-keyint 25 --scenecut 40 --bframes 16 --b-bias 0 --b-pyramid --b-rdo --bime --weightb --direct auto --qpmin 1 --qpmax 51 --qpstep 16 --ipratio 1.4 --pbratio 1.3 --chroma-qp-offset 0 --direct-8x8 1 --partitions i4x4,i8x8,p8x8,b8x8 --me umh --merange 40 --subme 7 --mixed-refs --8x8dct --trellis 1 --no-fast-pskip --deadzone-inter 11 --deadzone-intra 11 --threads auto --thread-input --filter -2,-1 --no-psnr --no-ssim --progress --fps 25 --output "D:\sx264\quant21.mp4" D:\sx264\test.avs 640x352

Quant 15 liefert:

Zitat

x264 [info]: slice I:29 Avg QP:13.29 size: 29254 PSNR Mean Y:49.21 U:50.80 V:52.31 Avg:49.83 Global:49.64
x264 [info]: slice P:869 Avg QP:14.76 size: 13843 PSNR Mean Y:47.00 U:49.49 V:50.85 Avg:47.80 Global:47.75
x264 [info]: slice B:1759 Avg QP:16.35 size: 4225 PSNR Mean Y:45.98 U:49.19 V:50.67 Avg:46.92 Global:46.87
x264 [info]: mb I I16..4: 38.5% 37.6% 23.9%
x264 [info]: mb P I16..4: 11.6% 7.1% 2.7% P16..4: 29.0% 26.8% 21.4% 0.0% 0.0% skip: 1.4%
x264 [info]: mb B I16..4: 0.9% 1.1% 0.3% B16..8: 24.8% 3.3% 6.9% direct: 4.6% skip:58.0%
x264 [info]: 8x8 transform intra:35.8% inter:46.9%
x264 [info]: direct mvs spatial:99.4% temporal:0.6%
x264 [info]: ref P 47.9% 18.5% 8.4% 5.9% 3.4% 3.9% 2.3% 1.9% 1.2% 1.5% 0.9% 1.2% 0.8% 0.9% 0.7% 0.6%
x264 [info]: ref B 66.3% 15.2% 4.8% 3.5% 1.9% 2.1% 1.2% 1.1% 0.7% 0.8% 0.5% 0.6% 0.4% 0.5% 0.3%
x264 [info]: SSIM Mean Y:0.9864254
x264 [info]: PSNR Mean Y:46.348 U:49.306 V:50.745 Avg:47.240 Global:47.162 kb/s:1466.11

Alles anzeigen

quant15.mp4 (19,3MB)

Quant 18 liefert:

Zitat

x264 [info]: slice I:29 Avg QP:16.29 size: 19999 PSNR Mean Y:47.11 U:49.73 V:51.20 Avg:47.95 Global:47.73
x264 [info]: slice P:869 Avg QP:17.81 size: 7689 PSNR Mean Y:44.99 U:48.85 V:50.10 Avg:46.02 Global:45.94
x264 [info]: slice B:1759 Avg QP:19.61 size: 2163 PSNR Mean Y:44.51 U:48.69 V:49.90 Avg:45.58 Global:45.51
x264 [info]: mb I I16..4: 38.7% 39.1% 22.2%
x264 [info]: mb P I16..4: 4.1% 4.8% 1.8% P16..4: 45.0% 22.9% 17.6% 0.0% 0.0% skip: 3.9%
x264 [info]: mb B I16..4: 0.2% 0.2% 0.1% B16..8: 27.7% 1.9% 4.2% direct: 2.2% skip:63.6%
x264 [info]: 8x8 transform intra:43.7% inter:50.6%
x264 [info]: direct mvs spatial:99.7% temporal:0.3%
x264 [info]: ref P 51.4% 17.2% 9.3% 4.9% 3.4% 3.3% 2.4% 1.5% 1.2% 1.1% 0.9% 0.9% 0.7% 0.7% 0.6% 0.5%
x264 [info]: ref B 68.2% 14.2% 5.6% 3.1% 2.0% 1.8% 1.2% 0.8% 0.6% 0.6% 0.4% 0.4% 0.3% 0.4% 0.3%
x264 [info]: SSIM Mean Y:0.9822789
x264 [info]: PSNR Mean Y:44.698 U:48.749 V:49.976 Avg:45.750 Global:45.666 kb/s:798.81

Alles anzeigen

quant18.mp4 (10,5 MB)

Quant 21 liefert:

Zitat

x264 [info]: slice I:29 Avg QP:19.30 size: 13793 PSNR Mean Y:45.20 U:48.98 V:50.31 Avg:46.22 Global:45.96
x264 [info]: slice P:869 Avg QP:20.90 size: 4679 PSNR Mean Y:43.16 U:48.13 V:49.23 Avg:44.33 Global:44.21
x264 [info]: slice B:1759 Avg QP:22.85 size: 1274 PSNR Mean Y:43.00 U:47.99 V:48.97 Avg:44.16 Global:44.06
x264 [info]: mb I I16..4: 32.8% 49.1% 18.1%
x264 [info]: mb P I16..4: 3.0% 5.4% 1.1% P16..4: 53.6% 13.4% 12.3% 0.0% 0.0% skip:11.2%
x264 [info]: mb B I16..4: 0.1% 0.2% 0.1% B16..8: 23.8% 1.3% 2.8% direct: 1.1% skip:70.7%
x264 [info]: 8x8 transform intra:54.5% inter:58.6%
x264 [info]: direct mvs spatial:99.8% temporal:0.2%
x264 [info]: ref P 53.6% 16.9% 10.3% 4.2% 3.2% 2.9% 2.4% 1.1% 1.0% 0.9% 0.8% 0.7% 0.6% 0.6% 0.6% 0.3%
x264 [info]: ref B 71.4% 13.0% 5.6% 2.6% 1.8% 1.5% 1.1% 0.6% 0.5% 0.4% 0.4% 0.3% 0.3% 0.3% 0.2%
x264 [info]: SSIM Mean Y:0.9772481
x264 [info]: PSNR Mean Y:43.079 U:48.050 V:49.069 Avg:44.238 Global:44.123 kb/s:484.14

Alles anzeigen

quant21.mp4 (6,4MB)

Quant 24 liefert:

Zitat

x264 [info]: slice I:29 Avg QP:22.30 size: 9677 PSNR Mean Y:43.41 U:48.14 V:49.27 Avg:44.55 Global:44.24
x264 [info]: slice P:869 Avg QP:24.17 size: 2977 PSNR Mean Y:41.46 U:47.34 V:48.28 Avg:42.71 Global:42.54
x264 [info]: slice B:1759 Avg QP:26.16 size: 769 PSNR Mean Y:41.47 U:47.22 V:48.02 Avg:42.70 Global:42.55
x264 [info]: mb I I16..4: 33.2% 50.4% 16.3%
x264 [info]: mb P I16..4: 2.8% 4.4% 0.8% P16..4: 51.1% 9.1% 7.0% 0.0% 0.0% skip:24.7%
x264 [info]: mb B I16..4: 0.0% 0.1% 0.0% B16..8: 17.1% 0.9% 1.9% direct: 0.5% skip:79.4%
x264 [info]: 8x8 transform intra:53.4% inter:58.7%
x264 [info]: direct mvs spatial:99.5% temporal:0.5%
x264 [info]: ref P 55.7% 16.1% 11.6% 3.3% 3.0% 2.4% 2.4% 0.8% 0.8% 0.7% 0.6% 0.6% 0.6% 0.5% 0.5% 0.3%
x264 [info]: ref B 76.0% 11.4% 4.8% 2.0% 1.5% 1.1% 0.9% 0.5% 0.4% 0.3% 0.3% 0.3% 0.2% 0.3% 0.1%
x264 [info]: SSIM Mean Y:0.9709250
x264 [info]: PSNR Mean Y:41.485 U:47.268 V:48.115 Avg:42.723 Global:42.564 kb/s:304.72

Alles anzeigen

quant24.mp4 (4,05 MB)

Quant 27 liefert:

Zitat

x264 [info]: slice I:29 Avg QP:25.31 size: 6813 PSNR Mean Y:41.66 U:47.19 V:48.00 Avg:42.88 Global:42.51
x264 [info]: slice P:869 Avg QP:27.51 size: 1949 PSNR Mean Y:39.75 U:46.47 V:47.22 Avg:41.07 Global:40.84
x264 [info]: slice B:1759 Avg QP:29.20 size: 478 PSNR Mean Y:39.86 U:46.35 V:46.94 Avg:41.16 Global:40.97
x264 [info]: mb I I16..4: 41.6% 44.1% 14.3%
x264 [info]: mb P I16..4: 2.8% 3.8% 0.7% P16..4: 45.7% 6.7% 4.4% 0.0% 0.0% skip:35.8%
x264 [info]: mb B I16..4: 0.0% 0.1% 0.0% B16..8: 13.4% 0.6% 1.2% direct: 0.3% skip:84.4%
x264 [info]: 8x8 transform intra:49.7% inter:62.8%
x264 [info]: direct mvs spatial:97.9% temporal:2.1%
x264 [info]: ref P 56.5% 16.4% 12.4% 2.8% 2.8% 2.2% 2.4% 0.6% 0.7% 0.6% 0.6% 0.5% 0.5% 0.4% 0.5% 0.2%
x264 [info]: ref B 77.9% 10.7% 4.3% 1.8% 1.3% 1.0% 0.8% 0.4% 0.3% 0.3% 0.3% 0.2% 0.2% 0.2% 0.1%
x264 [info]: SSIM Mean Y:0.9625180
x264 [info]: PSNR Mean Y:39.845 U:46.401 V:47.043 Avg:41.147 Global:40.945 kb/s:197.23

Alles anzeigen

quant27.mp4 (2,63 MB)

Quant 30 liefert:

Zitat

x264 [info]: slice I:29 Avg QP:28.33 size: 4835 PSNR Mean Y:39.91 U:46.21 V:46.73 Avg:41.19 Global:40.77
x264 [info]: slice P:869 Avg QP:30.94 size: 1303 PSNR Mean Y:38.05 U:45.49 V:46.02 Avg:39.42 Global:39.16
x264 [info]: slice B:1759 Avg QP:32.15 size: 301 PSNR Mean Y:38.21 U:45.40 V:45.78 Avg:39.56 Global:39.35
x264 [info]: mb I I16..4: 48.6% 40.0% 11.4%
x264 [info]: mb P I16..4: 2.5% 3.6% 0.5% P16..4: 40.5% 4.8% 3.0% 0.0% 0.0% skip:45.1%
x264 [info]: mb B I16..4: 0.0% 0.1% 0.0% B16..8: 10.6% 0.3% 0.7% direct: 0.1% skip:88.2%
x264 [info]: 8x8 transform intra:50.1% inter:65.4%
x264 [info]: direct mvs spatial:96.2% temporal:3.8%
x264 [info]: ref P 56.5% 17.1% 13.1% 2.5% 2.5% 2.1% 2.2% 0.5% 0.6% 0.5% 0.5% 0.5% 0.5% 0.4% 0.5% 0.2%
x264 [info]: ref B 78.4% 11.0% 4.1% 1.6% 1.1% 1.0% 0.7% 0.4% 0.3% 0.3% 0.2% 0.2% 0.2% 0.2% 0.2%
x264 [info]: SSIM Mean Y:0.9519528
x264 [info]: PSNR Mean Y:38.180 U:45.440 V:45.869 Avg:39.534 Global:39.300 kb/s:130.07

Alles anzeigen

URL=http://www.filebam.com/download/46939-32f17f/quant30.mp4]quant30.mp4[/url] (1,74MB)

mit geändereten Deblocking-Einstellungen

Quant 21 Deblocking (0/0) liefert:

Zitat

x264 [info]: slice I:29 Avg QP:19.30 size: 13793 PSNR Mean Y:45.17 U:49.05 V:50.42 Avg:46.21 Global:45.95
x264 [info]: slice P:869 Avg QP:20.92 size: 4630 PSNR Mean Y:43.21 U:48.10 V:49.20 Avg:44.36 Global:44.24
x264 [info]: slice B:1759 Avg QP:22.89 size: 1267 PSNR Mean Y:43.04 U:47.96 V:48.93 Avg:44.19 Global:44.08
x264 [info]: mb I I16..4: 32.8% 49.1% 18.1%
x264 [info]: mb P I16..4: 2.7% 4.8% 1.0% P16..4: 54.8% 13.1% 11.9% 0.0% 0.0% skip:11.7%
x264 [info]: mb B I16..4: 0.1% 0.1% 0.1% B16..8: 23.7% 1.4% 2.8% direct: 1.0% skip:70.9%
x264 [info]: 8x8 transform intra:54.2% inter:58.4%
x264 [info]: direct mvs spatial:99.8% temporal:0.2%
x264 [info]: ref P 54.5% 15.6% 10.6% 4.0% 3.3% 2.9% 2.5% 1.1% 1.0% 0.9% 0.8% 0.7% 0.7% 0.6% 0.6% 0.3%
x264 [info]: ref B 72.0% 12.2% 5.9% 2.5% 1.9% 1.5% 1.1% 0.6% 0.5% 0.4% 0.4% 0.3% 0.3% 0.3% 0.2%
x264 [info]: SSIM Mean Y:0.9772872
x264 [info]: PSNR Mean Y:43.116 U:48.022 V:49.034 Avg:44.266 Global:44.148 kb/s:480.14

Alles anzeigen

quant21_0_0.mp4 (6,37 MB)

Quant 24 Deblocking (1/0) liefert:

Zitat

x264 [info]: slice I:29 Avg QP:22.30 size: 9677 PSNR Mean Y:43.41 U:48.17 V:49.31 Avg:44.55 Global:44.24
x264 [info]: slice P:869 Avg QP:24.17 size: 2970 PSNR Mean Y:41.48 U:47.31 V:48.24 Avg:42.72 Global:42.55
x264 [info]: slice B:1759 Avg QP:26.15 size: 767 PSNR Mean Y:41.47 U:47.20 V:47.96 Avg:42.69 Global:42.55
x264 [info]: mb I I16..4: 33.2% 50.4% 16.3%
x264 [info]: mb P I16..4: 2.7% 4.2% 0.8% P16..4: 51.3% 9.0% 7.1% 0.0% 0.0% skip:24.8%
x264 [info]: mb B I16..4: 0.0% 0.1% 0.0% B16..8: 17.2% 0.9% 1.8% direct: 0.5% skip:79.4%
x264 [info]: 8x8 transform intra:53.1% inter:58.7%
x264 [info]: direct mvs spatial:99.7% temporal:0.3%
x264 [info]: ref P 56.3% 15.0% 11.9% 3.2% 3.1% 2.4% 2.5% 0.8% 0.9% 0.7% 0.7% 0.6% 0.6% 0.5% 0.6% 0.3%
x264 [info]: ref B 76.2% 10.7% 4.9% 2.1% 1.5% 1.2% 1.0% 0.5% 0.5% 0.3% 0.3% 0.3% 0.2% 0.3% 0.1%
x264 [info]: SSIM Mean Y:0.9705626
x264 [info]: PSNR Mean Y:41.492 U:47.243 V:48.070 Avg:42.724 Global:42.563 kb/s:303.97

Alles anzeigen

quant24_1_0.mp4 (4,04 MB)

Quant 27 Deblocking (2/1) liefert:

Zitat

x264 [info]: slice I:29 Avg QP:25.31 size: 6813 PSNR Mean Y:41.55 U:47.20 V:48.02 Avg:42.78 Global:42.40
x264 [info]: slice P:869 Avg QP:27.52 size: 1961 PSNR Mean Y:39.68 U:46.47 V:47.20 Avg:41.01 Global:40.79
x264 [info]: slice B:1759 Avg QP:29.20 size: 484 PSNR Mean Y:39.78 U:46.35 V:46.90 Avg:41.08 Global:40.90
x264 [info]: mb I I16..4: 41.6% 44.1% 14.3%
x264 [info]: mb P I16..4: 2.8% 3.6% 0.7% P16..4: 46.4% 6.6% 4.6% 0.0% 0.0% skip:35.4%
x264 [info]: mb B I16..4: 0.0% 0.1% 0.0% B16..8: 13.6% 0.6% 1.2% direct: 0.2% skip:84.3%
x264 [info]: 8x8 transform intra:49.0% inter:62.5%
x264 [info]: direct mvs spatial:97.0% temporal:3.0%
x264 [info]: ref P 56.8% 15.4% 12.6% 2.8% 2.9% 2.2% 2.5% 0.6% 0.7% 0.6% 0.7% 0.5% 0.5% 0.5% 0.6% 0.2%
x264 [info]: ref B 77.4% 10.5% 4.5% 1.9% 1.4% 1.1% 0.9% 0.4% 0.4% 0.3% 0.3% 0.2% 0.2% 0.2% 0.1%
x264 [info]: SSIM Mean Y:0.9611511
x264 [info]: PSNR Mean Y:39.770 U:46.396 V:47.012 Avg:41.077 Global:40.875 kb/s:198.78

Alles anzeigen

quant27_2_1.mp4 (2,65 MB)

Quant 30 Deblocking (3/2) liefert:

Zitat

x264 [info]: slice I:29 Avg QP:28.33 size: 4836 PSNR Mean Y:39.74 U:46.22 V:46.73 Avg:41.04 Global:40.60
x264 [info]: slice P:869 Avg QP:30.92 size: 1316 PSNR Mean Y:37.94 U:45.49 V:46.01 Avg:39.32 Global:39.05
x264 [info]: slice B:1759 Avg QP:32.17 size: 307 PSNR Mean Y:38.09 U:45.39 V:45.77 Avg:39.44 Global:39.23
x264 [info]: mb I I16..4: 48.6% 40.0% 11.4%
x264 [info]: mb P I16..4: 2.6% 3.5% 0.4% P16..4: 41.0% 4.5% 3.2% 0.0% 0.0% skip:44.7%
x264 [info]: mb B I16..4: 0.0% 0.1% 0.0% B16..8: 10.8% 0.3% 0.7% direct: 0.1% skip:88.0%
x264 [info]: 8x8 transform intra:49.3% inter:65.5%
x264 [info]: direct mvs spatial:95.6% temporal:4.4%
x264 [info]: ref P 56.5% 16.3% 13.3% 2.5% 2.7% 2.1% 2.3% 0.6% 0.6% 0.5% 0.6% 0.5% 0.5% 0.4% 0.5% 0.2%
x264 [info]: ref B 78.0% 10.4% 4.6% 1.7% 1.2% 1.0% 0.8% 0.5% 0.4% 0.3% 0.3% 0.2% 0.2% 0.2% 0.1%
x264 [info]: SSIM Mean Y:0.9496183
x264 [info]: PSNR Mean Y:38.056 U:45.430 V:45.861 Avg:39.420 Global:39.186 kb/s:131.64

Alles anzeigen

quant30_3_2.mp4 (1,77MB)

Anmerkungen:
1. eine aktuelle x264 Version wurde verwendet
2. die Quelle ist auf Grund ihrer Lichtwechsel für MPEG-4 nicht gerade angenehm zu encoden
3. den Deblocker hatte ich erst auf -2,-1 gelassen und ihm in 2ten Teil für einige Encodes erhöht, um zu sehen ob höheres Beblocking für niedrigere Quantizer eventuell sinnig ist
4. Hoffe der FileHoster ist brauchbar,...
4. die Deutung dieser Beispiele kann wer anders übernehmen

Cu Selur

Ps.: sehe gerade der Titel dreht sich ja nun um 'Transparenz-Qualität' -> ab wann ein Encode Transparenz liefert am Quantizer fest zu machen halte ich für gewagt, würde da eher versuchen Transparenz an einem SSIM-Wert festzumachen.

Denkt aber daran, dass diese Formel nichts weiter als einen groben Anhaltspunkt bietet. ASP und AVC sind zu unterschiedlich als dass man so einfach umrechnen und dann ein ähnliches Ergebnis erwarten könnte.

Vielleicht sollte man in diesem Zusammenhang auch den mittleren Quantisierungsfehler betrachten. Der ist bei einer Schrittweite von s - wenn mich mein Signalverarbeitungs-Wissen nicht ganz im Stich lässt - (s^2)/12. Die Quantisierer-Schrittweite ist bei AVC 1,25*2^((QP-6)/6) = s. Wenn man das in (s^2)/12 einsetzt kann man sich den mittleren Quantisierungsfehler ausrechnen. Sagt natürlich weit weniger aus als ein SSIM-Wert, das ist klar, aber als Anhaltspunkt sei es allemal erwähnt.
Zur eigentlichen Frage des Topic-Erstellers: ich habe die Erfahrung gemacht, dass die "Transparenz" je nach Bewegtheit des Videomaterials irgendwo um QP 14 liegt - wobei es stellenweise Ausnahmen gibt, in denen Artefakte auftreten, die einem bei (ganz) genauer Betrachtung auffallen.

Dust Signs