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Video compression for the web « Behind the Scenes

Video compression for the web

September 11th, 2009

This is a brief guide to compressing video for today’s free video-hosting sites.

Compressing video for the web is something that we deal with daily at Backstar. As a result, I have become familiar with many free video hosting websites, and with their respective best-practices for compression. Here’s a bit of what I’ve learned…

A Leveled Playing Field

The technical differences between such sites as YouTube, Vimeo, Blip.tv, and others have been reduced dramatically with recent developments.

  • High quality 720p modes like YouTube’s HQ and Vimeo’s HD have brought up the level of quality seen in both SD and HD resolution videos
  • Flash support for the H.264 codec has solidified it as the codec to use for online video

Thus, the differences have been distilled to file size / duration limits and non-technical considerations such as target audience, video player customization, and embedding features.

I will only be dealing with the technical considerations here.

Compression Settings

These settings should serve you well when uploading to almost any video hosting site. The exceptions to this rule are true streaming sites (see the note about CBR/VBR below) and sites that do not recompress your videos upon uploading (such as when hosting videos on your own website).

In general, if the service is free then these settings will work just fine.

SD SD-wide HD
Resolution 640×480 853×480 1280×720
Video Codec H.264 H.264 H.264
Video Bitrate* 2000 Kbps 2500 Kbps 5000 Kbps
VBR / CBR VBR VBR VBR
Audio Codec AAC AAC AAC
Audio Bitrate 128 128 128
Framerate 29.97 29.97 29.97


* sometimes you will need to reduce the bitrate in order to get your video under a site’s file size restrictions.

Other Tips

(in no particular order)

  • If the source video is interlaced, deinterlace it or risk having jagged edges and other artifacting.
  • Always use the source file for compressions (do not, if possible, recompress an already compressed file). Each time you compress a video you lose some of the audio/image quality.
  • 2-pass VBR is always better than 1-pass VBR. If you have the option, and a bit more time, take it.
  • If you have to reduce the resolution, try to use multiples of 16 (ex: 320×240). I believe this has to do with the size of the macroblocks used by H.264 codecs.
  • If you are hosting the video on a site that offers real streaming (not the pseudo streaming offered by YouTube, Vimeo, Facebook, and others like them) then you will want to use CBR (constant bitrate) rather than VBR (variable bitrate).
  • If audio quality is really important, bump the audio bitrate up to 196 Kbps.

File Size / Duration Limits

Here are the resource limitations of some of the major free video hosting websites:

YouTube Vimeo* Facebook Blip.tv
Size Limit 2 GB 500 MB 1 GB 1 GB
Duration 10 min Unlimited 20 min Unlimited

* this information pertains to the free (basic) Vimeo account

Yeah, I know Facebook isn’t often seen as a video hosting platform, but it’s up there in the top 5 most visited sites on the internet, and it hosts video, so it felt necessary to include it.



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