I have a small compression mystery. I have with my Canon XH A1 two clips, the same length and synonymous motifs / audio, even in HDV and even DV (4:3) rotated. All in the respective right track in Final Cut Express, then packed and compressed with FCE, so Quicktime Compression (H.264 codec, 480 * 270 for HDV, 320 * 240 for DV, settings remaining the same). The comic, the film with DV as the starting material is of the file size more than twice as large as that of the HDV had its origin. I've already synonymous with the other codecs probiert (eg Sorensen), but always the same. my "little" 320 * 240 movies is always more than twice as large in megabytes. Am a bit confused. How can that be? Or is this another case of anfängerhaftem mistake ;-)
gruss matthias
Antwort von tommyb:
And the sound was compressed or synonymous of the original clip on?
Antwort von joerg-emil:
.... a really interesting effect. ...
I can see that with my semi-dangerous perhaps be explained. HD is already a compressed format and is required on the DV tape does not need more memory than DV (ie around 12 GB per hour). Let's assume that both Rohfilm 10 GB Space show.
In the following I consider only the first reduction of the resolution:
If the HD Resolutiondes Films of 1440x1080 (1,555 MP) to 480x270 (129 MP) reduces, reduces the data volume by approximately 92%. The HD file would be about 0.8 GB in size.
Reduces the Resolutiondes DV Films of 768x576 (442 MP) at 320x240 (77 MP) reduces the data volume by only about 83%. The DV file would then be 1.7 GB in size.
Now, of course, the other compression techniques are used, but the sheer amount of data is output in the computer hardware higher.
.... or was subject to a mistake I am now ....
Greetings from the Rhine Jörg-Emil
Antwort von tommyb:
@ joerg-emil DV and HDV use different compression algorithms, ie, the comparison can not be made.
DV = Intra frame, each picture is stored separately HDV = Inter frame, multiple images are to a Group of Pictures summarized
These points but can be problematic: - Bit rate among non-identical codecs (DV has more)
- Video was not deinterlaced the HDV video has finer interlace lines during runterskalieren completely disappear without many artifacts left behind. The DV - but video is a little more than half being reduced, not so many interlace lines are removed.
- Sound was not compressed or transferred from the original DV stores uncompressed sound with 1536 kbit / s, HDV, however, 384 kbit / s (according to Wiki). If the sound is unchanged, the DV File naturally larger
Antwort von indy:
So the sound, I have compressed (MPEG 4 - AAC) and forgot the whole thing times synonymous with interlace / deinterlace probiert. 320er This file is in all cases is still significantly larger ...
Antwort von Daigoro:
If the videos have the same duration, but one is twice as big, the synonymous ne twice as high data rate, thus can not all be the same settings.
Somewhere you have an 'automatic', 'best' or 'Variable data' checkbox, which does what it wants.
