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THIS IS AN OLD (1998) VERSION
In http://mediateca.elis.org you can find a newer one

To watch the videos you need the Free RealPlayer

NETTUNO courses

Sintesi dei contenuti del corso Docenti Video in formato MPP
Reti di calcolatori Prof. Silvano Gai (Politecnico di Torino) 20 Kpbs - 28.8 modem 50 Kpbs - 56K modem or ISDN

COMPARING DIFFERENT ENCODING SCHEMES

The source is a 20 seconds clip, taken from a VHS cassette (which was recorded with a S-VHS camera), played through a Panasonic SVHS NV-HS1000 videorecorder, using a S-Video cable. The encoding was done on a Windows NT 4.0 Hewlett-Packard Kayak XU (Pentium II 300 Mhz), directly from the videorecorder, using an Osprey 100 video card, with version 1.2 driver and these settings.

filename

target bitrate

actual bitrate

buffer time

average frames per second

size

band for audio

RealEncoder optimization

Panasonic setting

Software precompression

20-192-6.5-m-so-v75.rm

20000

22367

3,6

7,8

192x144

6,5

medium

sharp

Video1 at 75

20-192-6.5-f5-so-v75.rm

20000

19082

1

4,8

192x144

6,5

fixed 5 fps

sharp

Video1 at 75

20-192-8.5-f5-so-v75.rm

20000

19425

1,1

4,8

192x144

8,5

fixed 5 fps

sharp

Video1 at 75

20-192-6.5-sh-so-v75.rm

20000

21329

3,4

4,3

192x144

6,5

sharpest

sharp

Video1 at 75

20-192-8.5-sh-so-v75.rm

20000

21850

3,7

4,0

192x144

8,5

sharpest

sharp

Video1 at 75

20-192-5-sh-so-v75.rm

20000

22459

3,4

4,4

192x144

5

sharpest

sharp

Video1 at 75

20-192-5-sh-sh-v75.rm

20000

23019

4,2

3,5

192x144

5

sharpest

sharp

Video1 at 75

20-192-5-f4-m-v75.rm

20000

19969

2,3

3,8

192x144

5

fixed 4 fps

middle

Video1 at 75

20-192-5-m-m-v75.rm

20000

23174

4

7,0

192x144

5

medium

middle

Video1 at 75

20-192-5-sh-m-no.rm

20000

22249

4,1

4,0

192x144

5

sharpest

middle

No compression

20-192-5-sh-m-v0.rm

20000

21808

4,1

3,9

192x144

5

sharpest

middle

Video1 at 0

20-192-5-sh-m-v100.rm

20000

22990

4,2

3,8

192x144

5

sharpest

middle

Video1 at 100

20-192-5-sh-m-v75.rm

20000

22357

3,7

3,8

192x144

5

sharpest

middle

Video1 at 75

20-160-5-sh-m-v75.rm

20000

20941

2,9

4,2

160x120

5

sharpest

middle

Video1 at 75

20-288-5-sh-m-v75.rm

20000

23197

5,6

4,0

288x216

5

sharpest

middle

Video1 at 75

20-384-5-sh-m-v75.rm

20000

23345

9,7

1,1

384x288

5

sharpest

middle

Video1 at 75

20-192-8.5-sh-m-v75.rm

20000

22725

4,4

3,5

192x144

8,5

sharpest

middle

Video1 at 75

45-192-8.5-sh-m-v75.rm

45000

47474

2

5,5

192x144

8,5

sharpest

middle

Video1 at 75

filename
the filenames follow this notation:

target bitrate size band for audio RealEncoder optimization Panasonic optimization software precompression
  width in pixels   sh = optimize sharpest
m = optimize middle
sm = optimize smoothest
f5 = fixed 5 frame per second
so = soft
m= middle
sh = sharp
no = frames not compressed
v75 = Microsoft Video 1 with  compression at level 75 (always with 1 key frame every 15 frames)


target bitrate
The requested bitrate before encoding.

actual bitrate
The actual bitrate after encoding. Sometimes it is higher than the requested, because of the selected options which cause higher requirements.

buffer time
Produced by the encoder

average frames per second
The actual result after encoding.

size
In pixels. Both sides must be multiple of 16, with the exception of the allowed 160x120.

band for audio
Reserved band for audio. 5, 6.5 and 8.5 kbps all have a frequency response of 4 Khz.

RealEncoder optimization
The setting during the encoding. It can optimize the quality of the image (sharpest) or the movement (smoothest) or try a best solution (middle). The alternative is to fix a frame rate.

Panasonic setting
The Panasonic videorecorder has the capability of softening or sharpening the image, while playing a cassette. The "middle" setting does not change the source.

Software precompression
The Osprey 100 (which has not any hardware compression capability) has an Option/Set video compression which let you choose if you want to compress via software while encoding. This means that, using the RealEncoder, there is a double compression: first the one set by Osprey and then the Real one. The RealEncoder manual suggests not to use any compression.