meaning of mbits/mbps

meaning of mbits/mbps

Okay, "mbits" (or megabits) is a measure of the amount of data where 8 bits traditionally equal one byte of data. On the other hand, "mbps" is a measure of rate or the flow of data per unit of time -- in this case 1 mbps equals 1,000,000 bits per second (1.0 x 10^6 if using base 10 counting or 1.0 x 10^20 if using base 2 counting).

Converted to h264 (via MPEG Streamclip) and mbits now are 10.83. Trying to understand what this means. Output looks very much like original but only about 5% the original size. Should I care about this?

H.264 is a very efficient and versatile codec having a wide range of data rate use. You may see it used at very low data rates for the e-mailing of small display video files (<100 kbps audio+video) to iPod (1.5-1.7 Mbps audio+video) to TV (2.5-5.0 Mbps audio + video) to HD movie trailers (8.0-12.0 Mbps audio+video) to unlimited SD/editing quality (16.0-20.0 Mbps audio+video) to HD (80.0-120.0 Mbps audio+video). If you are referring to HDV at 30 fps then an HD data rate of 118 Mbps would be normal for the actual data contained in the HDV file. However, this data is encapsulated in an MPEG-2 wrapper which reduces the bandwidth to that of normal DV data rate for tape storage/capture via firewire. Depending on the actual H.264 output dimensions, a 10.83 Mbps conversion with little or no "visual" loss in quality is quite normal and be the same as turning your original recorded file(s) into the equivalent of an an Apple HD movie trailer.
Not sure if this helps or really answers the intent of your original question

The mbps is the number of bits each second of video is using to store the file and thus on playback you see the bitrate - each second of that HV30 clip is using 118 megabits(or roughly 14.75 MegaBytes) to store its data . Higher bitrates, all other things being equal, look better. Generally.

With different codecs (H.264 is your codec you used to export) lower bitrates can look quite good as you found out.

Your 10.83 mbps is not even a tenth of the original bitrate so the file is not even 1/10th the size.

DVD's from Hollywood use MPEG-2 as the codec and use bitrates around 6-8 mbps and look OK - even though the source digital video might have been 200-300 mb/sec. You can get better quality with H.264 at lower bitrates which is why H.264 is the base standard for HD DVD video.

If you have an iPod you encode at only 1.5 mbps for 640X480 video and it looks great using H.264, and even on a TV set it is quite watchable, not much worse than a DVD, yet it is only 20-25% of the DVD bitrate. Shows how old the MPEG-2 codec is . I connect my iPod (5G and Touch) to a TV set when I travel and the video is as good as what's on TV.