1. A variable bitrate video encoding method comprising, for encoding a sequence of frames, at least a quantization step of an input bitstream, a coding step of said quantized bitstream, and a control step of the quantization step with respect to a buffer occupancy at the output of said coding step, said method being characterized in that it also comprises an analysis step, for defining on the basis of parameters related to said input bitstream a reserve of bits (ROBC) periodically updated at each frame, and an additional control step, for maintaining, increasing or decreasing the quantization step value according to the state of said reserve of bits.
2. An encoding method according to claim 1, characterized in that the quantization stepvalue is modified only if said reserve of bits reaches critical values.
3. An encoding method according to claim 2, characterized in that the evolution of the initial quantization step Q_INIT with respect to the state of the reserve (ROBC) is given by the following relations:
If (ROBC<0) and (S1<ROBCTFBB<S2)
then QQ_INITV1
If (ROBC<0) and (S2<ROBCTFBB<S3)
then QQ_INITV2
If (ROBC<0) and (S3<ROBCTFBB<S4)
then QQ_INITV3
If (ROBC<0) and (S4<ROBCTFBB<S5)
then QQ_INITV4
If (ROBC<0) and (S5<ROBCTFBB<S6)
then QQ_INIT V5
If (ROBC<0) and (S6<ROBCTFBB<S7)
then QQ_INITV6
If (ROBC<0) and (S7<ROBCTFBB)
then QQ_INITV7
If (ROBC>0) and (T1<ROBCTFBB)
then QQ_INITV8
Else ROBCQ_INIT
where S1 to S7 are thresholds of increasing value, T1 is also a threshold, and V1 to V8 are the variations of said initial quantization step.
4. An encoding method according to claim 3, characterized in that said thresholds S1 to S7 are equal to (0,07; 0,15; 0,27; 0,4; 0,5; 0,6; 0,7) respectively, T1 is equal to (0,1) and said variations V1 to V8 are respectively equal to 2, 4, 6, 8, 10, 12, 14 and 1.
5. An encoding device allowing to implement an encoding method according to anyone of claims 1 to 4.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. Process for purification of polyester containing impurities, these impurities containing at least 0.1% residual monomer(s) by weight of polyester, comprising at least the step of:
(ii) adding to the polyester in a solvent a functionalised material chosen from a PAMAM dendrimer and a resin functionalised by a primary andor secondary amine function or functions
2. Process according to claim 1 additionally comprising the steps of:
(iii) eliminating the functionalised material;
(iv) eliminating the solvent.
3. Process according to one of claim 1 or 2, in which the polyester is chosen from a polycaprolactone (PCL), a lactic acid polymer (PLA), a lactic and glycolic acid polymer (PLGA) and a glycolic acid polymer (PGA).
4. Process according to one of claims 1 to 3, in which the polyester is a lactic acid polymer (PLA) or a lactic acid and glycolic acid polymer (PLGA).
5. Process according to one of claims 1 to 4, in which the functionalised material is a resin, preferably a resin functionalised by a primary amine function or functions.
6. Process according to claim 5, in which the functionalised resin used in step (ii) has the formula (I)
S-L \u2003\u2003(I)
in which L is a linear or branched C1 to C15 alkyl chain or an aralkyl chain, in which one or more carbon atoms are replaced by a nitrogen atom,
given that two successive carbon atoms cannot both be replaced by a nitrogen atom, and
given that at least one terminal carbon atom is replaced by a nitrogen atom,
and S is an appropriate support.
7. Process according to claim 6, in which S is a polystyrene or polystyrene-divinyl benzene support.
8. Process according to one of claims 1 to 7, in which step (iii) is carried out by filtration.
9. Process according to one of claims 1 to 8, in which step (iv) is carried out by drying, preferably by vacuum evaporation.
10. Process according to one of claims 1 to 9 for purification of polyester containing impurities, these impurities additionally containing at least 0.1% residual catalyst by weight of polyester, additionally comprising the step of:
(i) adding a weak base anion exchange resin to the polyester in a solvent.
11. Process according to claim 10, in which step (i) is repeated a second time.
12. Process according to one of claim 10 or 11, in which the anion exchange resin is chosen from Amberlyst\xae A21, Dowex\u2122 66, Amberlite FPA53, Amberlite FPA55, Amberlite CR5550 or IMAC HP661 resin.
13. Process according to one of claims 10 to 12, in which the anion exchange resin is then eliminated by filtration.
14. Polyester (co)polymerisation process comprising the steps of:
(a) placing the monomer(s) in contact with an acidic catalyst in a solvent;
(b) treating the obtained polyester according to step (i) as defined in claims 10 to 13;
(c) treating the obtained polyester according to steps (ii) to (iv) as defined in claims 1 to 9.