• Compression Techniques

  Recommended FFmpeg command for converting videos to iPhone/Android

  Posted by Guillermo Carrion on April 1, 2011 at 11:55 am

  Hi!

  I’m setting up a CentOS Server with FFmpeg to convert source FLV (and soon MP4/H264) videos to MP4/H264/AAC compatible mainly with iPhone and Android devices (and new devices that support H264/AAC) to be streamed using Wowza Streaming Server over 3G mobile networks.

  Currently we do our video conversion on a Windows Machine with FFmpeg and the following command:
  ffmpeg.exe -i source_video.flv -y -vcodec libx264 -s qvga -acodec libfaac -ab 96k -ac 2 -b 200K -threads 4 -flags +loop -cmp +chroma -partitions 0 -me_method epzs -subq 1 -trellis 0 -refs 1 -coder 0 -me_range 16 -g 300 -keyint_min 25 -sc_threshold 40 -i_qfactor 0.71 -maxrate 10M -bufsize 10M -rc_eq 'blurCplx^(1-qComp)' -qcomp 0.6 -qmin 10 -qmax 51 -qdiff 4 -level 30 target_video.mp4

  That command was done by a co-worker a couple years ago and its working fine on the tests I’ve done.

  However since I’m installing this new server with the latest version of FFmpeg, I wanted to know if I could optimize that command for better results in this Linux server with the latest FFmpeg.

  I tried the above command on my new server and produced similar results as I used to produce in the Windows machine setup.

  Here is the meta data from a sample video I produced using the above command on my new Linux setup.
  
General
Complete name : ffmpeg_test.mp4
Format : MPEG-4
Format profile : Base Media
Codec ID : isom
File size : 5.08 MiB
Duration : 2mn 39s
Overall bit rate : 268 Kbps
Writing application : Lavf52.64.2

  Video
  ID : 1
  Format : AVC
  Format/Info : Advanced Video Codec
  Format profile : Baseline@L3.0
  Format settings, CABAC : No
  Format settings, ReFrames : 1 frame
  Codec ID : avc1
  Codec ID/Info : Advanced Video Coding
  Duration : 2mn 39s
  Bit rate mode : Variable
  Bit rate : 200 Kbps
  Width : 320 pixels
  Height : 240 pixels
  Display aspect ratio : 4:3
  Frame rate mode : Constant
  Frame rate : 30.000 fps
  Color space : YUV
  Chroma subsampling : 4:2:0
  Bit depth : 8 bits
  Scan type : Progressive
  Bits/(Pixel*Frame) : 0.087
  Stream size : 3.96 MiB (78%)
  Writing library : x264 core 107
  Encoding settings : cabac=0 / ref=1 / deblock=1:0:0 / analyse=0x1:0 / me=dia / subme=1 / psy=1 / psy_rd=0.00:0.00 / mixed_ref=0 / me_range=16 / chroma_me=1 / trellis=0 / 8x8dct=0 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=0 / threads=4 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / constrained_intra=0 / bframes=0 / weightp=0 / keyint=300 / keyint_min=25 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=abr / mbtree=1 / bitrate=200 / ratetol=20.0 / qcomp=0.60 / qpmin=10 / qpmax=51 / qpstep=4 / vbv_maxrate=10000 / vbv_bufsize=10000 / ip_ratio=1.41 / aq=1:1.00 / nal_hrd=none

  Audio
ID : 2
Format : AAC
Format/Info : Advanced Audio Codec
Format profile : LC
Codec ID : 40
Duration : 2mn 39s
Bit rate mode : Variable
Bit rate : 55.8 Kbps
Channel(s) : 2 channels
Channel positions : Front: L R
Sampling rate : 22.05 KHz
Compression mode : Lossy
Stream size : 1.06 MiB (21%)


  What do you think?

  Could that command be optimized for better results?

  Thanks!

  Michael Rampe replied 15 years, 4 months ago 2 Members · 4 Replies
• 4 Replies

• 

  Michael Rampe

  April 1, 2011 at 10:23 pm

  [Guillermo Carrion] “Could that command be optimized for better results?”

  Most definitely. Which version of FFmpeg and Wowza are you using for this project? seems quite old due to lack of a -vpre for x264. Funnily enough, I am also currently doing work on getting wowza to stream to iphones and other mobile devices.

  Anyway, I think you could achieve much better quality using a main profile, higher bitrate and larger size.

  Michael
• 

  Guillermo Carrion

  April 1, 2011 at 11:01 pm

  Hi!

  The FFmpeg version I’m running on my new Linux CentOS Server is: FFmpeg version 0.6.1

  About Wowza, I believe is version: 2.2 (is provided by NetDNA/HDDN)

  However, the command in my previous post, was done maybe over two years ago by a co-worker. That’s because I want to know if there is any other new commands to achieve better optimized results.

  thanks
• 

  Guillermo Carrion

  April 1, 2011 at 11:05 pm

  Michael Rampe: “Anyway, I think you could achieve much better quality using a main profile, higher bitrate and larger size.”

  Do you have a sample command to achieve this?
  About the larger size, I would prefer not going too much large, because is for mobile streaming over 3G, and I want to take in consideration slow 3G when low reception and all that. 😉
• 

  Michael Rampe

  April 2, 2011 at 12:34 am

  you will find the x264 presets in the ffpresets folder. Try some different ones and then limit to main profile as a second vpre option.

  eg “-vpre fast -vpre main”

  Michael

Reply to this Discussion! Login or Sign Up