DHOB (IU5SGN): Compressione video

martedì 29 ottobre 2013

Compressione video

Il video originale dell'intervento al Linux Day 2013 e' stato ripreso con una micro camera Go Pro a risoluzione Full HD. Il risultato e' che l'intervento della durata di circa 16 minuti corrisponde ad una occupazione su disco di circa 3.7 Gb... un po' troppo per pensare di effettuare l'upload su Youtube

Ho quindi provato a comprimere il file mediante il software ffmpeg e la seguente stringa

ffmpeg -i luca.mp4 -s 720x480 -acodec copy luca.mkv

al termine della compressione il file e' risultato essere di circa 30 Mb con una compressione di oltre un fattore 1000. La conversione e' stata fatta su un IBM T61 dual core con 2 Giga di Ram e per ogni secondo di video erano necessari circa 3-4 secondi di calcolo

Ecco l'output del programma per verificare i settaggi

-----------------------------------------------------------------

n Oct 3 2013 05:43:15 with gcc 4.8 (Debian 4.8.1-10)

configuration: --prefix=/usr --extra-cflags='-g -O2 -fstack-protector --param=ssp-buffer-size=4 -Wformat -Werror=format-security ' --extra-ldflags='-Wl,-z,relro' --cc='ccache cc' --enable-shared --enable-libmp3lame --enable-gpl --enable-nonfree --enable-libvorbis --enable-pthreads --enable-libfaac --enable-libxvid --enable-postproc --enable-x11grab --enable-libgsm --enable-libtheora --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libx264 --enable-libspeex --enable-nonfree --disable-stripping --enable-libvpx --enable-libschroedinger --disable-encoder=libschroedinger --enable-version3 --enable-libopenjpeg --enable-librtmp --enable-avfilter --enable-libfreetype --enable-libvo-aacenc --disable-decoder=amrnb --enable-libvo-amrwbenc --enable-libaacplus --libdir=/usr/lib/x86_64-linux-gnu --disable-vda --enable-libbluray --enable-libcdio --enable-gnutls --enable-frei0r --enable-openssl --enable-libass --enable-libopus --enable-fontconfig --enable-libpulse --disable-mips32r2 --disable-mipsdspr1 --dis libavutil 52. 18.100 / 52. 18.100

libavcodec 54. 92.100 / 54. 92.100

libavformat 54. 63.104 / 54. 63.104

libavdevice 54. 3.103 / 54. 3.103

libavfilter 3. 42.103 / 3. 42.103

libswscale 2. 2.100 / 2. 2.100

libswresample 0. 17.102 / 0. 17.102

libpostproc 52. 2.100 / 52. 2.100

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'GOPR1892.MP4':

Metadata:

major_brand : avc1

minor_version : 0

compatible_brands: avc1isom

creation_time : 2013-10-26 11:49:18

Duration: 00:16:32.17, start: 0.000000, bitrate: 30117 kb/s

Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuvj420p, 1920x1080 [SAR 1:1 DAR 16:9], 29972 kb/s, 47.95 fps, 47.95 tbr, 720k tbn, 95.90 tbc

Metadata:

creation_time : 2013-10-26 11:49:18

handler_name : GoPro AVC

Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s

Metadata:

creation_time : 2013-10-26 11:49:18

handler_name : GoPro AAC

[libx264 @ 0x18fe4e0] using SAR=32/27

[libx264 @ 0x18fe4e0] using cpu capabilities: MMX2 SSE2Fast SSSE3 Cache64 SlowShuffle

[libx264 @ 0x18fe4e0] profile High, level 3.1

[libx264 @ 0x18fe4e0] 264 - core 138 - H.264/MPEG-4 AVC codec - Copyleft 2003-2013 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00

Output #0, matroska, to 'output.mkv':

Metadata:

major_brand : avc1

minor_version : 0

compatible_brands: avc1isom

encoder : Lavf54.63.104

Stream #0:0(eng): Video: h264 (H264 / 0x34363248), yuvj420p, 720x480 [SAR 32:27 DAR 16:9], q=-1--1, 1k tbn, 47.95 tbc

Metadata:

creation_time : 2013-10-26 11:49:18

handler_name : GoPro AVC

Stream #0:1(eng): Audio: aac ([255][0][0][0] / 0x00FF), 48000 Hz, stereo, 128 kb/s

Metadata:

creation_time : 2013-10-26 11:49:18

handler_name : GoPro AAC

Stream mapping:

Stream #0:0 -> #0:0 (h264 -> libx264)

Stream #0:1 -> #0:1 (copy)

Press [q] to stop, [?] for help

frame=47576 fps= 27 q=-1.0 Lsize= 30650kB time=00:16:32.17 bitrate= 253.1kbits/s

video:14525kB audio:15503kB subtitle:0 global headers:0kB muxing overhead 2.075269%

[libx264 @ 0x18fe4e0] frame I:192 Avg QP:20.59 size: 32206

[libx264 @ 0x18fe4e0] frame P:12016 Avg QP:23.02 size: 477

[libx264 @ 0x18fe4e0] frame B:35368 Avg QP:27.74 size: 84

[libx264 @ 0x18fe4e0] consecutive B-frames: 0.8% 0.1% 0.1% 99.0%

[libx264 @ 0x18fe4e0] mb I I16..4: 13.8% 42.8% 43.4%

[libx264 @ 0x18fe4e0] mb P I16..4: 0.1% 0.1% 0.0% P16..4: 6.7% 1.0% 1.1% 0.0% 0.0% skip:91.0%

[libx264 @ 0x18fe4e0] mb B I16..4: 0.0% 0.0% 0.0% B16..8: 3.7% 0.1% 0.0% direct: 0.0% skip:96.2% L0:23.5% L1:75.9% BI: 0.6%

[libx264 @ 0x18fe4e0] 8x8 transform intra:42.1% inter:67.2%

[libx264 @ 0x18fe4e0] coded y,uvDC,uvAC intra: 62.6% 71.2% 40.6% inter: 0.4% 1.1% 0.0%

[libx264 @ 0x18fe4e0] i16 v,h,dc,p: 11% 23% 5% 61%

[libx264 @ 0x18fe4e0] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu: 22% 23% 19% 4% 6% 5% 8% 5% 6%

[libx264 @ 0x18fe4e0] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 32% 22% 11% 5% 5% 6% 6% 6% 6%

[libx264 @ 0x18fe4e0] i8c dc,h,v,p: 48% 24% 23% 5%

[libx264 @ 0x18fe4e0] Weighted P-Frames: Y:3.1% UV:0.3%

[libx264 @ 0x18fe4e0] ref P L0: 78.7% 9.0% 9.8% 2.3% 0.2%

[libx264 @ 0x18fe4e0] ref B L0: 82.7% 16.4% 0.9%

[libx264 @ 0x18fe4e0] ref B L1: 96.7% 3.3%

[libx264 @ 0x18fe4e0] kb/s:119.92

luca@debian-T61:~/Desktop$ ls

100_PANA envi4.7.1 GOPR1892.MP4 Libri linux_day.odp Moddingstudio.pdf netbeans-7.3.desktop Nido_2013 problemi.txt~

asw-380 GOPR1891.MP4 landsat linux blue angel linux_day.pdf mondiali netbeans-c++.desktop output.mkv test.desktop

luca@debian-T61:~/Desktop$ ffmpeg -i GOPR1891.MP4 -s 720x480 -acodec copy output1.mkv

built on Oct 3 2013 05:43:15 with gcc 4.8 (Debian 4.8.1-10)

libavcodec 54. 92.100 / 54. 92.100

libavformat 54. 63.104 / 54. 63.104

libavdevice 54. 3.103 / 54. 3.103

libavfilter 3. 42.103 / 3. 42.103

libswscale 2. 2.100 / 2. 2.100

libswresample 0. 17.102 / 0. 17.102

libpostproc 52. 2.100 / 52. 2.100

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'GOPR1891.MP4':

Metadata:

major_brand : avc1

minor_version : 0

compatible_brands: avc1isom

creation_time : 2013-10-26 11:39:26

Duration: 00:09:46.22, start: 0.000000, bitrate: 30126 kb/s

Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuvj420p, 1920x1080 [SAR 1:1 DAR 16:9], 29975 kb/s, 47.95 fps, 47.95 tbr, 720k tbn, 95.90 tbc

Metadata:

creation_time : 2013-10-26 11:39:26

handler_name : GoPro AVC

Stream #0:1(eng): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 127 kb/s

Metadata:

creation_time : 2013-10-26 11:39:26

handler_name : GoPro AAC

[libx264 @ 0x1a9e4e0] using SAR=32/27

[libx264 @ 0x1a9e4e0] using cpu capabilities: MMX2 SSE2Fast SSSE3 Cache64 SlowShuffle

[libx264 @ 0x1a9e4e0] profile High, level 3.1

[libx264 @ 0x1a9e4e0] 264 - core 138 - H.264/MPEG-4 AVC codec - Copyleft 2003-2013 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=3 lookahead_threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=crf mbtree=1 crf=23.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00

Output #0, matroska, to 'output1.mkv':

Metadata:

major_brand : avc1

minor_version : 0

compatible_brands: avc1isom

encoder : Lavf54.63.104

Stream #0:0(eng): Video: h264 (H264 / 0x34363248), yuvj420p, 720x480 [SAR 32:27 DAR 16:9], q=-1--1, 1k tbn, 47.95 tbc

Metadata:

creation_time : 2013-10-26 11:39:26

handler_name : GoPro AVC

Stream #0:1(eng): Audio: aac ([255][0][0][0] / 0x00FF), 48000 Hz, stereo, 127 kb/s

Metadata: