Re-encoding at different quality
We are setting up a system where TV will be grabbed and encoded (MPEG-1, lavc+lavf+home code) at 2 bitrates: 600 and 1200 kbits video. If one of the sides fails, the other will have to used as backup; this leads to 2 questions: (1) Is there a way (maybe involving patches or hacks to lavc) to re-encode from 1200 to 600 using significantly less CPU than full decode and encode? (2) When re-encoding from 600 to 1200, how do I ensure the nominal bitrate is maintained? (I have to use VBR for reasons too long to explain). TIA. -- Michel Bardiaux R&D Director T +32 [0] 2 790 29 41 F +32 [0] 2 790 29 02 E mailto:mbardiaux at mediaxim.be Mediaxim NV/SA Vorstlaan 191 Boulevard du Souverain Brussel 1160 Bruxelles http://www.mediaxim.com/
Hi On Mon, Dec 26, 2005 at 02:31:59PM +0100, Michel Bardiaux wrote:
We are setting up a system where TV will be grabbed and encoded (MPEG-1, lavc+lavf+home code) at 2 bitrates: 600 and 1200 kbits video. If one of the sides fails, the other will have to used as backup; this leads to 2 questions:
(1) Is there a way (maybe involving patches or hacks to lavc) to re-encode from 1200 to 600 using significantly less CPU than full decode and encode?
motion vectors and macroblock types can easily and cleanly be reused you could also try to requentize blocks without any ME/MC but that wont look good with anything but very small keyframe intervalls
(2) When re-encoding from 600 to 1200, how do I ensure the nominal bitrate is maintained? (I have to use VBR for reasons too long to explain).
re-encoding from 600 to 1200 ? add zero bytes or something [...] -- Michael
Michel Bardiaux wrote:
We are setting up a system where TV will be grabbed and encoded (MPEG-1, lavc+lavf+home code) at 2 bitrates: 600 and 1200 kbits video. If one of the sides fails, the other will have to used as backup; this leads to 2 questions:
(1) Is there a way (maybe involving patches or hacks to lavc) to re-encode from 1200 to 600 using significantly less CPU than full decode and encode?
(2) When re-encoding from 600 to 1200 why areyou encoding from 600 to 1200. its not going to look any better. , how do I ensure the nominal bitrate is maintained? maybe try 2 pass encoding (I have to use VBR for reasons too long to explain).
TIA.
Mustafa wrote:
Michel Bardiaux wrote:
We are setting up a system where TV will be grabbed and encoded (MPEG-1, lavc+lavf+home code) at 2 bitrates: 600 and 1200 kbits video. If one of the sides fails, the other will have to used as backup; this leads to 2 questions:
(1) Is there a way (maybe involving patches or hacks to lavc) to re-encode from 1200 to 600 using significantly less CPU than full decode and encode?
(2) When re-encoding from 600 to 1200
why areyou encoding from 600 to 1200. its not going to look any better.
Do you really think I dont know that? Since we encode 24/7, we keep our videos by 15-minutes files. And they must be made so they can be concatenated. If I want to inject a 600kbps capture as replacement for a failed 1200kpbs capture, I need a file that looks like 1200 and quacks like 1200 :-) even if it's not a 1200.
, how do I ensure the nominal
bitrate is maintained?
maybe try 2 pass encoding (I have to use VBR for reasons too long to explain).
TIA.
-- Michel Bardiaux R&D Director T +32 [0] 2 790 29 41 F +32 [0] 2 790 29 02 E mailto:mbardiaux at mediaxim.be Mediaxim NV/SA Vorstlaan 191 Boulevard du Souverain Brussel 1160 Bruxelles http://www.mediaxim.com/
Michel Bardiaux wrote:
Mustafa wrote:
Michel Bardiaux wrote:
We are setting up a system where TV will be grabbed and encoded (MPEG-1, lavc+lavf+home code) at 2 bitrates: 600 and 1200 kbits video. If one of the sides fails, the other will have to used as backup; this leads to 2 questions:
(1) Is there a way (maybe involving patches or hacks to lavc) to re-encode from 1200 to 600 using significantly less CPU than full decode and encode?
(2) When re-encoding from 600 to 1200
why areyou encoding from 600 to 1200. its not going to look any better.
Do you really think I dont know that? sorry but id did think you did not know that.
Since we encode 24/7, we keep our
videos by 15-minutes files. And they must be made so they can be concatenated. If I want to inject a 600kbps capture as replacement for a failed 1200kpbs capture, I need a file that looks like 1200 and quacks like 1200 :-) even if it's not a 1200.
, how do I ensure the nominal
bitrate is maintained?
maybe try 2 pass encoding (I have to use VBR for reasons too long to explain).
TIA.
participants (3)
-
lordverminard＠gmail.com -
mbardiaux＠mediaxim.be -
michaelni＠gmx.at