Bitrate for Full HD
 

I realise this might be best placed in the Editing forums, however I am interested in comments from 5D owners.

The question is prompted by Phillip Bloom's latest blog post about the 'Above Skywalker film'. He has posted a 30 mb/s quicktime for download which I downloaded and took a look at. Its a nice clip - seems to not have the colour correction of the Vimeo version - so that actually looks nicer to me than the large file.

Recently I was playing with mp4 encode rates for 5D2 clips to see where the sweet spot is for the best quality. For Vimeo I use 7500kb/s (which Phillip Bloom used for his Day at the Races) and then load these onto my Sony PS3 for watching myself. DVDs are too much of a hassle I find. At 7.5mb/s I get a few artefacts but not too bad.

I recently encoded a few clips at 15mb/s and do not see a lot of difference from the Vimeo bitrate clips at 7.5. Fewer artefacts, but the play rate starts to chop even on the PS3. Apple state mp4 is FullHD at 8mb/s.

What do you think is 30mb/s noticeably better than the 7.5? The 5D records at somewhere near 40 - do we need to encode at that rate for full quality? How many people burn to Blu-Ray. Is it noticebly better than an mp4 on a hard disc?

* PS I know Vimeo guidelines are for 5mb/s HD mp4.

Regards

Jeff

It really depends a lot on content. I've had 5D footage look beautiful in full HD at 4mbps. Of course it was well lit (very little noise), largely static camera, and shallow depth of field so the only real detail was in the subject's faces. I've had other stuff that had noticeable artifacts even at 10mbps because of movement, detail and noise. Two-pass encoding can make a big difference - in fact one of the reasons footage can still look great at 1/3rd the camera's data rate is that the camera has to do the encoding in real time (and on battery power). With plenty of time and processing power you can maintain much better quality in a lower data rate.

That seems low. Is that for 720p or 1080p? SmugMug who we use for video hosting deliver 720p at about 3.2Mbps & 1080p at a little over 7Mbps. I usually compress to 8-10Mbps H.264 MPEG4 before uploading & the conversion to lower rates gets done by SmugMug. Here are some sample clips straight off the 5DII without editing converted using MPEG Streamclip & then uploaded Barkers Videos

Thanks for the replies
 

Thank you both for your replies, you have identified six key factors that affect the clarity in the video - bitrate, available light/aperture value, zooms, pans and rendered effects from the edit phase. The first factor depends on the other five.

I'll try a few at 10mb/s and see how they go.

On an aside I put a clip up at Vimeo from my AVCHD at 1080 and 7.5mb/s and it interlaced badly. I know their 1080 is expirimental but I am getting better results at 720.

With regards

Jeff