What is the best size for Flash video playback?

September 4, 2012 11:38 AM

I am having a bit of a challenge getting through to our developers about the correct size for a Flash video player for our sites.

We encode h264 video in mp4 containers, and play them in a home-made Flash player (not OSMF). We encode the videos at 640x360 but play them in a video player sized 912x513. We also encode some other video at 854x480 and play it in the same 912x513 player.

I am looking for some back up on convincing our developers to build a player that is the right size for the video, or at the very least have playback dimensions that are divisible by 16 (or 8) and are the same divisibility as the video frame dimensions. Anyone have any good resources I can point them too that will speak to better performance of video playback if done right?

posted by kilikina73 to technology (5 answers total)

I have found, through personal experience, that the best playback performance for h.264 encoded material is in scales where both dimensions are divisible by 4. Odd sizes tend to cause playback at lower fps and/or dropped frames, particularly on playback devices that are older, not powerful or taxed in some way. I believe that this is because most codecs encode and decode using blocks. Older codecs wanted divisibility by 16 for best playback but the more recent h.264 standards use variable block sizes down to a minimum of 4.

I dug up a wikipedia page that describes a bit about how the codec works in blocks (along with other info). I'd think that if your dev team is interested in the best playback performance, they'll want to use div by 16 scales.
posted by bz at 12:40 PM on September 4, 2012

640x360 is what I use for web video. I can punch out some tight mp4s that look great at that resolution and have a very reasonable bitrate. Not sure what the bitrate would increase when scaled up to 912x513, but its not insignificant. I think they're just erring on the side of caution to make sure Grandma's 1mps DSL line can watch the video comfortably. Or over Joe Poweruser's 3G card.

I'd invest in a player that can specify HD and SD. SD by default doing 640x360 and your higher res video playable only by clicking on the HD button. I think both Flowplayer and JWPlayer support this.
posted by damn dirty ape at 12:50 PM on September 4, 2012

Why are you using a custom built flash player in the first place? Sometimes the best way to work with a recalcitrant developer (and I say this as an occasionally recalcitrant developer) is to work around them instead of with them.
posted by ook at 2:00 PM on September 4, 2012

What did the developers say when you asked them to do it? It sounds like you're looking for a response to them saying 'it won't make performance better', is that right?
posted by jacalata at 8:35 PM on September 4, 2012

Who signs their paychecks? That is the person who could easily convince them to do the right thing.
posted by anon4now at 9:42 PM on September 4, 2012