[MEncoder-users] H.264 compression

Wed May 14 11:07:21 CEST 2008

Hi,

For 6 months or so I've been using the lavcopts in the command below to 
make rather nice quality H.264 video. Recently, after the update from 
Ubuntu Gusty to Hardy broke mencoder, I recompiled libx264 and 
mplayer/mencoder and the files produced are about half the size that 
they used to be.

Previously mencoder produced H.264 at about 760 Mbps, now it creates 
H.264 at about 360 Mbps. To my eyes I feel that the quality has reduced, 
but I thought that setting vq* to 2 should give me a constant quality.

It might be that, since I know the files are smaller I think the quality 
is worse - us humans are odd like that - but I'm wondering if I've 
overlooked a change in the last few months that would mean my lavcopts 
less than optimal.

The full command I am using is (please excuse the line wrapping):

  mencoder -v \
   "$i" \
   -o "$d" \
   -aspect 1050:576 \
   -ofps 25.00 \
   -noskip \
   -mc 0 \
   -vfm ffmpeg \
   -vf kerndeint=18:0:0:1:0,crop=688:568:16:4,scale=480:272,harddup \
   -ovc lavc \
   -oac lavc \
   -lavcopts 
vglobal=1:vcodec=libx264:vqscale=2:vqmin=2:level=30:mbd=2:trell:v4mv:last_pred=2:dia=-1:vmax_b_frames=0:cmp=3:subcmp=3:autoaspect:aglobal=1:acodec=libfaac:abitrate=128 
\
   -of lavf \
   -lavfopts format=ipod

And here is the typical output (I pressed ^C after a couple of seconds 
of encoding)

MEncoder dev-SVN-r26759-4.2.3 (C) 2000-2008 MPlayer Team
CPU: Intel(R) Pentium(R) 4 CPU 3.20GHz (Family: 15, Model: 2, Stepping: 9)
CPUflags: Type: 15 MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
Compiled for x86 CPU with extensions: MMX MMX2 SSE SSE2

Configuration: --enable-gui --enable-menu
init_freetype
get_path('font/font.desc') -> '/home/mdsh/.mplayer/font/font.desc'
font: can't open file: /home/mdsh/.mplayer/font/font.desc
font: can't open file: /usr/local/share/mplayer/font/font.desc
Using MMX (with tiny bit MMX2) Optimized OnScreenDisplay
[file] File size is 1558312960 bytes
STREAM: [file] input.mpg
STREAM: Description: File
STREAM: Author: Albeu
STREAM: Comment: based on the code from ??? (probably Arpi)
success: format: 0  data: 0x0 - 0x5ce1f800
LAVF_check: MPEG PS format
Checking for YUV4MPEG2
ASF_check: not ASF guid!
Checking for NuppelVideo
Checking for REAL
Checking for SMJPEG
Searching demuxer type for filename input.mpg ext: .mpg
Checking for Nullsoft Streaming Video
Checking for MOV
Checking for VIVO
header block 1 size: 0
AVS: avs_check_file - attempting to open file input.mpg
AVS: File is too big, aborting...
Checking for PVA
Checking for MPEG-TS...
TRIED UP TO POSITION 86857, FOUND 47, packet_size= 0, SEEMS A TS? 0
Checking for LMLM4 Stream Format
Invalid packet in LMLM4 stream: ch=0 size=1140851708
LMLM4 Stream Format not found
system stream synced at 0xD (13)!
==> Found video stream: 0
==> Found audio stream: 0
MPEG-PS file format detected.
Searching for sequence header... OK!
VIDEO:  MPEG2  720x576  (aspect 3)  25.000 fps  4350.0 kbps (543.8 kbyte/s)
[V] filefmt:2  fourcc:0x10000002  size:720x576  fps:25.000  ftime:=0.0400
==========================================================================
Opening audio decoder: [mp3lib] MPEG layer-2, layer-3
dec_audio: Allocating 4608 + 65536 = 70144 bytes for output buffer.
mp3lib: using SSE optimized decore!
MP3lib: init layer2&3 finished, tables done
MPEG 1.0, Layer II, 48000 Hz 256 kbit Stereo, BPF: 768
Channels: 2, copyright: No, original: No, CRC: Yes, emphasis: 0
AUDIO: 48000 Hz, 2 ch, s16le, 256.0 kbit/16.67% (ratio: 32000->192000)
Selected audio codec: [mp3] afm: mp3lib (mp3lib MPEG layer-2, layer-3)
==========================================================================
[file] File size is 0 bytes
STREAM: [file] input.mp4
STREAM: Description: File
STREAM: Author: Albeu
STREAM: Comment: based on the code from ??? (probably Arpi)
** MUXER_LAVF 
*****************************************************************
REMEMBER: MEncoder's libavformat muxing is presently broken and can generate
INCORRECT files in the presence of B-frames. Moreover, due to bugs MPlayer
will play these INCORRECT files as if nothing were wrong!
*******************************************************************************
OK, exit.
ALLOCATED STREAM N. 1, type=0
Opening video filter: [expand osd=1]
Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
Opening video filter: [harddup]
Opening video filter: [scale w=480 h=272]
SwScale params: 480 x 272 (-1=no scaling)
Opening video filter: [crop w=688 h=568 x=16 y=4]
Crop: 688 x 568, 16 ; 4
Opening video filter: [kerndeint=18:0:0:1:0]
==========================================================================
Trying to force video codec driver family ffmpeg...
Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
INFO: libavcodec init OK!
Selected video codec: [ffmpeg2] vfm: ffmpeg (FFmpeg MPEG-2)
==========================================================================
ALLOCATED STREAM N. 2, type=1
Building audio filter chain for 48000Hz/2ch/s16le -> 0Hz/0ch/??...
[libaf] Adding filter dummy
[dummy] Was reinitialized: 48000Hz/2ch/s16le
[libaf] Adding filter format
[format] Changing sample format from little-endian 16-bit signed int to 
big-endian 8-bit signed int
[dummy] Was reinitialized: 48000Hz/2ch/s16le
[format] Changing sample format from little-endian 16-bit signed int to 
big-endian 8-bit signed int
Building audio filter chain for 48000Hz/2ch/s16le -> 48000Hz/2ch/s16le...
[dummy] Was reinitialized: 48000Hz/2ch/s16le
[format] Changing sample format from little-endian 16-bit signed int to 
big-endian 8-bit signed int
[libaf] Removing filter format
[dummy] Was reinitialized: 48000Hz/2ch/s16le
Increasing filtered audio buffer size from 0 to 4224
[ffmpeg] aspect_ratio: 1.777778
VDec: vo config request - 720 x 576 (preferred colorspace: Planar YV12)
Trying filter chain: kerndeint crop scale harddup expand lavc
VDec: using Planar YV12 as output csp (no 0)
Movie-Aspect is 1.82:1 - prescaling to correct movie aspect.
VO Config (720x576->1050x576,flags=0,'MPlayer',0x32315659)
REQ: flags=0x441  req=0x0
REQ: flags=0x441  req=0x400
SwScaler: reducing / aligning filtersize 7 -> 8
SwScaler: reducing / aligning filtersize 7 -> 8
SwScaler: reducing / aligning filtersize 10 -> 9
SwScaler: reducing / aligning filtersize 10 -> 9
[swscaler @ 0x876bb98]BICUBIC scaler, from yuv420p to yuv420p using MMX2
[swscaler @ 0x876bb98]using 8-tap MMX scaler for horizontal luminance 
scaling
[swscaler @ 0x876bb98]using 8-tap MMX scaler for horizontal chrominance 
scaling
[swscaler @ 0x876bb98]using n-tap MMX scaler for vertical scaling (YV12 
like)
[swscaler @ 0x876bb98]688x568 -> 480x272
REQ: flags=0x401  req=0x0
REQ: flags=0x401  req=0x0
REQ: flags=0x401  req=0x0
videocodec: libavcodec (480x272 fourcc=34363268 [h264])
[VE_LAVC] High quality encoding selected (non-realtime)!
[VE_LAVC] Using constant qscale = 2.000000 (VBR).
[libx264 @ 0x87833f0]using SAR=1/1
[libx264 @ 0x87833f0]using cpu capabilities: MMX MMX2 SSE SSE2 Cache64
*** [kerndeint] Allocating mp_image_t, 720x576x12bpp YUV planar, 622080 
bytes
*** [kerndeint] Allocating mp_image_t, 720x576x12bpp YUV planar, 622080 
bytes5 D/B/S 0/1/0
*** [crop] Allocating mp_image_t, 720x576x12bpp YUV planar, 622080 bytes
*** [crop] Allocating mp_image_t, 720x576x12bpp YUV planar, 622080 bytes
*** [scale] Exporting mp_image_t, 688x568x12bpp YUV planar, 586176 bytes
*** [harddup] Allocating mp_image_t, 480x272x12bpp YUV planar, 195840 bytes
*** [expand] Exporting mp_image_t, 480x272x12bpp YUV planar, 195840 bytes
*** [lavc] Allocating mp_image_t, 480x272x12bpp YUV planar, 195840 bytes
get_path('subfont.ttf') -> '/home/mdsh/.mplayer/subfont.ttf'
Unicode font: 255 glyphs.
get_path('subfont.ttf') -> '/home/mdsh/.mplayer/subfont.ttf'
Unicode font: 255 glyphs.
Muxer frame buffer sending 25 frame(s) to the muxer.
VIDEO CODEC ID: 28
AUDIO CODEC ID: 15002, TAG: 0
MUXER_LAVF(audio stream) frame_size: 1024, scale: 1024, sps: 48000, 
rate: 48000, ctx->block_align = stream->wf->nBlockAlign; 0=1 
stream->wf->nAvgBytesPerSec:13078
Writing header...
*** [kerndeint] Allocating mp_image_t, 720x576x12bpp YUV planar, 622080 
bytes25 D/B/S 0/1/0
*** [crop] Allocating mp_image_t, 720x576x12bpp YUV planar, 622080 bytes
Pos:   3.8s     96f ( 0%)  32fps Trem:  30min  57mb  A-V:0.000 [82:127] 
A/Vms 2/26 D/B/S 0/1/0
Flushing video frames.
Writing index...

Video stream:   82.345 kbit/s  (10293 B/s)  size: 39114 bytes  3.800 
secs  96 frames

Audio stream:  127.423 kbit/s  (15927 B/s)  size: 67959 bytes  4.267 secs
Uninit audio filters...
[libaf] Removing filter dummy
Uninit audio: mp3lib
Uninit video: ffmpeg
[libx264 @ 0x87833f0]slice I:1     Avg QP:25.00  size:   432
[libx264 @ 0x87833f0]slice P:94    Avg QP:28.54  size:   412
[libx264 @ 0x87833f0]mb I  I16..4: 100.0%  0.0%  0.0%
[libx264 @ 0x87833f0]mb P  I16..4:  4.3%  0.0%  0.0%  P16..4: 22.0% 
0.0%  0.0%  0.0%  0.0%    skip:73.7%
[libx264 @ 0x87833f0]final ratefactor: -12.14
[libx264 @ 0x87833f0]SSIM Mean Y:0.9772701
[libx264 @ 0x87833f0]kb/s:82.3

Thanks

-- 
Mark