[FFmpeg-user] Changing aspect ratios

[littlebat]

On Tue, 1 Jan 2013 23:25:40 +0200
Anatol <anatol2002 at gmail.com> wrote:

> 640x480 ==> 4:3
> 
> Roku probably does not support anamorphic pixel.
> Retranscode it to 854x480
> 
> On Tue, Jan 1, 2013 at 9:44 PM, Yan Seiner <yan at seiner.com> wrote:
> 
> > I have a bunch of movies with the aspect ratio messed up.  The
> > container correctly identifies the aspect ratio, but the pixel
> > ratio is wrong.  These are for playback on a Roku.
> >
> > Width                                    : 640 pixels
> > Height                                   : 480 pixels
> > Display aspect ratio                     : 16:9
> >
> > I tried MP4Box, but even then my Roku doesn't show them correctly.
> >
> > These are encoded as h264 files in an mp4 container.  What's the
> > best way to re-encode them with the correct aspect ratio?
> >
> > Full info on the files (from mediainfo):
> >
> > General
> > Format                                   : MPEG-4
> > Format profile                           : Base Media
> > Codec ID                                 : isom
> > File size                                : 1.04 GiB
> > Duration                                 : 1h 48mn
> > Overall bit rate mode                    : Variable
> > Overall bit rate                         : 1 371 Kbps
> > Writing application                      : Lavf52.103.0
> >
> > Video
> > ID                                       : 1
> > Format                                   : AVC
> > Format/Info                              : Advanced Video Codec
> > Format profile                           : Baseline at L3.0
> > Format settings, CABAC                   : No
> > Format settings, ReFrames                : 5 frames
> > Format settings, GOP                     : N=1
> > Codec ID                                 : avc1
> > Codec ID/Info                            : Advanced Video Coding
> > Duration                                 : 1h 48mn
> > Bit rate                                 : 1 200 Kbps
> > Width                                    : 640 pixels
> > Height                                   : 480 pixels
> > Display aspect ratio                     : 16:9
> > Frame rate mode                          : Constant
> > Frame rate                               : 23.976 fps
> > Color space                              : YUV
> > Chroma subsampling                       : 4:2:0
> > Bit depth                                : 8 bits
> > Scan type                                : Progressive
> > Bits/(Pixel*Frame)                       : 0.163
> > Stream size                              : 937 MiB (88%)
> > Writing library                          : x264 core 114
> > Encoding settings                        : cabac=0 / ref=5 /
> > deblock=1:0:0 / analyse=0x1:0x111 / me=umh / subme=8 / psy=1 /
> > psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 /
> > trellis=1 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 /
> > chroma_qp_offset=-2 / threads=3 / sliced_threads=0 / nr=0 /
> > decimate=1 / interlaced=0 / constrained_intra=0 / bframes=0 /
> > weightp=0 / keyint=250 / keyint_min=25 / scenecut=40 /
> > intra_refresh=0 / rc_lookahead=50 / rc=abr / mbtree=1 /
> > bitrate=1200 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 /
> > qpstep=4 / ip_ratio=1.41 / aq=1:1.00
> >
> > Audio
> > ID                                       : 2
> > Format                                   : AAC
> > Format/Info                              : Advanced Audio Codec
> > Format profile                           : LC
> > Codec ID                                 : 40
> > Duration                                 : 1h 48mn
> > Bit rate mode                            : Variable
> > Bit rate                                 : 160 Kbps
> > Channel(s)                               : 2 channels
> > Channel positions                        : Front: L R
> > Sampling rate                            : 48.0 KHz
> > Compression mode                         : Lossy
> > Delay relative to video                  : 83ms
> > Stream size                              : 124 MiB (12%)
> >
> >
> >
> > __________
try:
ffmpeg -i inputfilename \
-vcodec libx264 -vpre slow -vpre baseline \
-b 1600k -s 854x480 -aspect 854:480 -r 23.976 \
-acodec copy \
-f mp4 outputfilename

Maybe need some modification for lastest ffmpeg.