| author | Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com> |
| Fri, 16 Apr 2010 15:15:52 +0300 | |
| changeset 8 | 4a7fac7dd34a |
| permissions | -rw-r--r-- |
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8
4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
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1 |
The Smoke Codec |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
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2 |
--------------- |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
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3 |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
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4 |
This is a very simple compression algorithm I was toying with when doing a |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
5 |
Java based player. Decoding a JPEG in Java has acceptable speed so this codec |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
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tries to exploit that feature. The algorithm first compares the last and the |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
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new image and finds all 16x16 blocks that have a squared difference bigger than |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
8 |
a configurable threshold. Then all these blocks are compressed into an NxM JPEG. |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
9 |
The quality of the JPEG is inversely proportional to the number of blocks, this |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
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way, the picture quality degrades with heavy motion scenes but the bitrate stays |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
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more or less constant. |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
12 |
Decoding decompresses the JPEG and then updates the old picture with the new |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
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blocks. |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
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15 |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
16 |
TODO: |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
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17 |
---- |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
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18 |
- make format extensible |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
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- motion vectors |
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4a7fac7dd34a
Revision: 201011
Dremov Kirill (Nokia-D-MSW/Tampere) <kirill.dremov@nokia.com>
parents:
diff
changeset
|
20 |
- do some real bitrate control |