Batch transcoding/re-encoding script

[mike503]

I have a ton of video files, all in various formats, various bitrates, various sizes. A lot are in higher quality than I really care to keep around and archive (waste of space)

I am looking to get a script created, ideally could run cross platform, but Linux shell is preferred.

It would:
1) Use a "sane" bitrate or quality factor (to be determined; I have videos that are 10-15x smaller than their 1080p counterparts and look just as good to me for normal viewing)
2) Reduce the resolution as necessary
3) Maintain the original aspect ratio and frame rate. Basically just downsize the video and allow some quality loss (that's only really noticeable the larger the video is blown up)

I'd be willing to toss a few bucks at the right solution too

For example I have a video with the specs below and it is about 90% of what I am looking for. Just need to know the ideal command line, and then maybe a couple tweaks or suggestions. I probably want to bump up the video quality a little bit... having a single variable to adjust would be nice. Audio doesn't need to be anything special - 128k maximum is good.

This is a nearly 26 minute video that is 166MB. I think I could live with 10 minutes being roughly 150MB, so I could easily double this video size (get a little more quality) - but I definitely don't need 12.6Mbps 3.5 gig 40 minute videos ;p

Tips/thoughts/command line tool suggestions? It mainly gets tricky for me when having to deal with aspect ratios. It seems like the original tool that created the sample video left in a bunch of flags, but I am not sure which are reasonable, which tool is better to use (mencoder, ffmpeg, HandbrakeCLI) etc.

Any help is appreciated!

General
Complete name                            : D:\video.mp4
Format                                   : MPEG-4
Format profile                           : Base Media
Codec ID                                 : isom
File size                                : 166 MiB
Duration                                 : 25mn 54s
Overall bit rate mode                    : Variable
Overall bit rate                         : 896 Kbps
Writing application                      : Lavf55.21.100

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L3.1
Format settings, CABAC                   : Yes
Format settings, ReFrames                : 4 frames
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 25mn 54s
Bit rate                                 : 803 Kbps
Width                                    : 720 pixels
Height                                   : 404 pixels
Display aspect ratio                     : 16:9
Original display aspect ratio            : 16:9
Frame rate mode                          : Constant
Frame rate                               : 29.970 fps
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Bits/(Pixel*Frame)                       : 0.092
Stream size                              : 149 MiB (90%)
Writing library                          : x264 core 140 r2377 1ca7bb9
Encoding settings                        : 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=18 / lookahead_threads=3 / 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=21.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / ip_ratio=1.40 / aq=1:1.00
Language                                 : English

Audio
ID                                       : 2
Format                                   : AAC
Format/Info                              : Advanced Audio Codec
Format profile                           : LC
Codec ID                                 : 40
Duration                                 : 25mn 54s
Bit rate mode                            : Variable
Bit rate                                 : 84.4 Kbps
Maximum bit rate                         : 128 Kbps
Channel(s)                               : 2 channels
Channel positions                        : Front: L R
Sampling rate                            : 44.1 KHz
Compression mode                         : Lossy
Delay relative to video                  : 67ms
Stream size                              : 15.7 MiB (9%)
Language                                 : English

[Baldrick]

You can pretty easy shrink all video with same video and audio bitrate.

But it gets much more complex if you want to adjust resolution. You need a script that reads the source information and so.

Do you have any programming skills? Perl? PHP? dos batch? Java??

[mike503]

Procedural PHP, can hack some bash around. I could write a php based one if I knew all the individual commands to strand together. Or bash.

[Baldrick]

You could then use

http://ffmpeg-php.sourceforge.net/

After you installed it works like

$movie = new ffmpeg_movie("filepath");
$width	= $movie->getFrameWidth();
$height	= $movie->getFrameHeight();

and then loop through all your video files and create ffmpeg commands:
http://www.phpro.org/tutorials/Video-Conversion-With-FFMPEG.html



Or ask Selur ( creator of hybrid) to make a complete program/script for you.

[mike503]

Thanks, at one point I used ffmpeg-php, but then it became too unstable. Not sure how robust it is now. I still wind up not necessarily getting things right (I sorta don't trust myself. "Scene rip packs" seem to work magically, usually, whereas what I do I am not sure)

[Baldrick]

ffmpeg-php doesn't seem to be updated since 2008...maybe not that good.

[Budman1]

For videos as you mentioned, that I do not mind the size and quality so much, I use one I wrote that is for trimming but will do whole movie if you leave the times 000. It uses FFMpeg and has defaults that can be changed to others in FFmpeg. It copies what I want or the whole video in whatever format the original was unless the box is checked in the lower right to force it to a format. It's a work in progress so far but it hasn't failed me yet. Quality is adjusted as qscale or CRF depending on the codec. It pulls info on original file and pads and crops to keep aspect correct for whatever you put in the resolution. If the video is 640x480 and you want 720x480, you are going to get pillar bars since it's already 480. It creates the script in a pseudo dos window and lets you change or add if you are familiar with FFMpeg.
Sound like what you were trying to do?

ADDED INFO : BTW.. the cursor location is to assist in using the delogo settings.