Understanding compression
Posted: Tue Mar 14, 2017 8:59 pm
Hello! Something that I've been wondering about and researching it can be difficult. My understanding of compression back in the days of SD was that for example if I were to make a DVD from an SD video, the DVD format would be a compressed version of the original but because of the codec the compression would allow for full quality of said original footage. In that the DVD would look as good as the original. However, if I were to re import said DVD footage, footage that has already been compressed, and then pick it apart and make a new storyboard/timeline, and then make a new DVD, the footage would get compressed again, and result in a DVD with inferior quality.
So DVD has a bit rate (in Normal or medium quality) of 4 to 7 Mbps. Before render booster, Arabesk would make a Blu Ray disc with a bit rate of 25 - 30 Mbps. And my cameras shoot at a similar bit rate. Now with render booster bit rates range from maybe 8 - 16 Mbps, making the file smaller and allowing for longer videos on Blu Ray discs.
So my question is, before render booster, Arabesk was churning out discs with a bit rate very close to the original footage. Was it re compressing the footage at all? I can add video in many formats with many different varying bit rates into the storyboard with Bogart. But when I go to make the final disc, or video data file, or whatever, how does Arabesk treat video with a compression rate that is equal too or better than, or worse than, the bit rate that the final video my Cassie produces? Another way to say it, lets say I import a video file with a bit rate of 28Mbps, and produce a video file say .avi, at 30 Mbps, then I re import said .avi file and keep editing, am I really using an inferior data file than the original footage? If all my video in a storyboard is made up of various videos with various bit rates, does the compression work equally on all parts of the video? Or does it only compress the parts that would normally be too large for the file and only compresses those parts that need to be?
For example, if I import a .mp4 with a bit rate of 8mbps and some original footage at 28Mbps, and my final video file will have a bit rate of 15 mbps, does this really only affect the original footage since it's going from 28Mbps to 15Mbps and if anything the .mp4 would look the same, as now it's bit rate has increased by almost twice its original size.
Follow?
So DVD has a bit rate (in Normal or medium quality) of 4 to 7 Mbps. Before render booster, Arabesk would make a Blu Ray disc with a bit rate of 25 - 30 Mbps. And my cameras shoot at a similar bit rate. Now with render booster bit rates range from maybe 8 - 16 Mbps, making the file smaller and allowing for longer videos on Blu Ray discs.
So my question is, before render booster, Arabesk was churning out discs with a bit rate very close to the original footage. Was it re compressing the footage at all? I can add video in many formats with many different varying bit rates into the storyboard with Bogart. But when I go to make the final disc, or video data file, or whatever, how does Arabesk treat video with a compression rate that is equal too or better than, or worse than, the bit rate that the final video my Cassie produces? Another way to say it, lets say I import a video file with a bit rate of 28Mbps, and produce a video file say .avi, at 30 Mbps, then I re import said .avi file and keep editing, am I really using an inferior data file than the original footage? If all my video in a storyboard is made up of various videos with various bit rates, does the compression work equally on all parts of the video? Or does it only compress the parts that would normally be too large for the file and only compresses those parts that need to be?
For example, if I import a .mp4 with a bit rate of 8mbps and some original footage at 28Mbps, and my final video file will have a bit rate of 15 mbps, does this really only affect the original footage since it's going from 28Mbps to 15Mbps and if anything the .mp4 would look the same, as now it's bit rate has increased by almost twice its original size.
Follow?
,the codecs worlds is confusing 