[FFmpeg-user] Unsophisticated user has a question

Tue Aug 13 05:51:12 CEST 2013

1. Get newer ffmpeg - 0.8.6 is quite old one. In your case - get newer x264
- it is 2 years old!. There is quite significant quality improvement with
newer ffmpeg/x264.
2. You may try h264 high profile (vs main that u use now) and/or you may
try 2-pass conversion.
3. Make up your mind what is the max bitrate that u can afford. Use - '-b
BITRATE -maxrate BITRATE' to set it.
4. Try those before digging further into crf, qscale, qmin, qmax, ...

x4 bitrate factor between h264 and mpeg2 makes sense, h264 should provide
fairly equal VISUAL quality.

On Sun, Aug 11, 2013 at 3:39 PM, ffmpeg at riventree.com
<riventree at gmail.com>wrote:

> Hello all,
>
> I've encountered something that makes me suspicious that I've lost data. I
> have a .MOD file (Grrr Cannon vidcams) that takes up 39M of storage. I
> converted it to .mp4 with the simplest possible command:
>
> jde-desktop% ffmpeg -i 002.MOD 002.mp4
>
> And the resultant .mp4 is 9.9M!
>
> A cursory (and uninformed) glance at the output shows a [720x480 / yuv420p
> / 29.97fps] stream in and the same thing out. The video input is
> "mpeg2video" and the output is "libx264", the audio is AC3 in and AAC out.
>
> *I need to know if that's just better packing or (this is the problem) I've
> lost data in the conversion.*
>
> How can I find out?
>
> Below is the complete output from ffmpeg. Can anyone explain the 4x size
> difference with the data there?
>
> -Jeff
>
> ffmpeg version 0.8.6-4:0.8.6-0ubuntu0.12.04.1, Copyright (c) 2000-2013 the
> Libav developers
>   built on Apr  2 2013 17:02:36 with gcc 4.6.3
> *** THIS PROGRAM IS DEPRECATED ***
> This program is only provided for compatibility and will be removed in a
> future release. Please use avconv instead.
> [mpeg @ 0x12699a0] max_analyze_duration reached
> Input #0, mpeg, from '002.MOD':
>   Duration: 00:00:05.97, start: 0.220756, bitrate: 5272 kb/s
>     Stream #0.0[0x1e0]: Video: mpeg2video (Main), yuv420p, 720x480 [PAR
> 32:27 DAR 16:9], 9600 kb/s, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
>     Stream #0.1[0x80]: Audio: ac3, 48000 Hz, stereo, s16, 256 kb/s
> [buffer @ 0x1271f60] w:720 h:480 pixfmt:yuv420p
> [libx264 @ 0x1271220] using SAR=32/27
> [libx264 @ 0x1271220] using cpu capabilities: MMX2 SSE2Fast SSSE3 Cache64
> [libx264 @ 0x1271220] profile Main, level 3.0
> [libx264 @ 0x1271220] 264 - core 120 r2151 a3f4407 - H.264/MPEG-4 AVC codec
> - Copyleft 2003-2011 - http://www.videolan.org/x264.html - options:
> cabac=1
> ref=3 deblock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=1 psy_rd=1.00:0.00
> mixed_ref=0 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11
> fast_pskip=1 chroma_qp_offset=-2 threads=1 sliced_threads=0 nr=0 decimate=1
> interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=0
> b_adapt=1 b_bias=0 direct=1 weightb=0 open_gop=1 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=1.25 aq=1:1.00
> Output #0, mp4, to '002.mp4':
>   Metadata:
>     encoder         : Lavf53.21.1
>     Stream #0.0: Video: libx264, yuv420p, 720x480 [PAR 32:27 DAR 16:9],
> q=-1--1, 30k tbn, 29.97 tbc
>     Stream #0.1: Audio: libvo_aacenc, 48000 Hz, stereo, s16, 200 kb/s
> Stream mapping:
>   Stream #0.0 -> #0.0
>   Stream #0.1 -> #0.1
> Press ctrl-c to stop encoding
> [mpeg2video @ 0x126ba40] warning: first frame is no keyframe
>     Last message repeated 1 times    734kB time=4.30 bitrate=1396.2kbits/s
>
> frame=  180 fps= 29 q=29.0 Lsize=     969kB time=5.97 bitrate=1328.6kbits/s
>
> video:816kB audio:147kB global headers:0kB muxing overhead 0.607864%
> frame I:1     Avg QP:24.04  size: 59660
> [libx264 @ 0x1271220] frame P:66    Avg QP:23.79  size: 10898
> [libx264 @ 0x1271220] frame B:113   Avg QP:28.92  size:   494
> [libx264 @ 0x1271220] consecutive B-frames:  3.3% 17.8% 63.3% 15.6%
> [libx264 @ 0x1271220] mb I  I16..4:  5.9%  0.0% 94.1%
> [libx264 @ 0x1271220] mb P  I16..4:  0.0%  0.0%  0.1%  P16..4: 62.1% 11.2%
> 11.3%  0.0%  0.0%    skip:15.4%
> [libx264 @ 0x1271220] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8: 34.0%  0.6%
>  0.1%  direct: 0.3%  skip:64.9%  L0:30.8% L1:59.4% BI: 9.8%
> [libx264 @ 0x1271220] coded y,uvDC,uvAC intra: 93.2% 91.8% 54.2% inter:
> 14.9% 16.3% 1.1%
> [libx264 @ 0x1271220] i16 v,h,dc,p: 26% 17% 15% 42%
> [libx264 @ 0x1271220] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu: 25% 14% 12%  6%  8%
> 10%  7% 10%  7%
> [libx264 @ 0x1271220] i8c dc,h,v,p: 44% 17% 31%  9%
> [libx264 @ 0x1271220] Weighted P-Frames: Y:0.0% UV:0.0%
> [libx264 @ 0x1271220] ref P L0: 63.4%  8.1% 16.6% 11.9%
> [libx264 @ 0x1271220] ref B L0: 85.8% 14.2%
> [libx264 @ 0x1271220] kb/s:1111.83
> jde-desktop%
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