Hi all,
First, I need to tell you that I am not familiar with the MPEG2 encoding
parameters
I am working on an application that needs to be able to encode a file to
a 60 Mbits MPEG2 CBR I-only file and it works pretty well.
Here are the ACodecContext encoding parameters I set :
//mybitrate has a value of 60 Mbits.
my_avcodeccontext_enc->bit_rate = mybitrate;//I want a 60 MBits/s file
my_avcodeccontext_enc->flags2 |= CODEC_FLAG2_STRICT_GOP;
my_avcodeccontext_enc->rc_max_rate = my_avcodeccontext_enc->bit_rate;//CBR
my_avcodeccontext_enc->rc_min_rate = my_avcodeccontext_enc->bit_rate;//CBR
my_avcodeccontext_enc->gop_size = 0;
my_avcodeccontext_enc->max_b_frames = 0;
my_avcodeccontext_enc->rc_buffer_size = ((40 *
(my_avcodeccontext_enc->bit_rate/1000000))/1.15) * 8 * 1024;//((40 *
my_avcodeccontext_enc->bit_rate)/1.15) / 1000000.0 * 8 * 1024;
my_avcodeccontext_enc->rc_initial_buffer_occupancy =
(my_avcodeccontext_enc->rc_buffer_size)*3/4;
my_avcodeccontext_enc->me_method = ME_EPZS;
my_avcodeccontext_enc->scenechange_threshold =
1000000000;//-sc_threshold 100000000
my_avcodeccontext_enc->mb_decision = FF_MB_DECISION_RD;//-mbd 2
my_avcodeccontext_enc->lmax = 340*FF_QP2LAMBDA;
my_avcodeccontext_enc->flags |= CODEC_FLAG_CBP_RD;//cbp
my_avcodeccontext_enc->flags |= CODEC_FLAG_TRELLIS_QUANT;//trell
Now I want to generate a MPEG2 IBP 60 Mbits file with a gop size of 10
and max_b_frame = 2. I tested many different settings but no one works
as I expect. I always end up with a file that has I, B and P frames that
have approximatively the same size. I know it depends of the content I
want to encode and that I want is a I frame with a bigger size than the
I frame encoded with the settings I used for I only encoding and B, P
frame with a lower size.
So basicaly, how to get a high quality 60 Mbits/s IBP MPEG2 file ?
Please read below to see the last parameters I tried for IBP encoding :
//mybitrate has a value of 60 Mbits.
my_avcodeccontext_enc->bit_rate = mybitrate;//I want a 60 MBits/s file
my_avcodeccontext_enc->flags2 |= CODEC_FLAG2_STRICT_GOP;
my_avcodeccontext_enc->rc_max_rate = my_avcodeccontext_enc->bit_rate *
2;//To let the encoder making bigger I frames.
my_avcodeccontext_enc->rc_min_rate = my_avcodeccontext_enc->bit_rate /
2;//To let the encoder making smaller B and P frames
my_avcodeccontext_enc->gop_size = 10;
my_avcodeccontext_enc->max_b_frames = 2;
my_avcodeccontext_enc->rc_buffer_size = ((40 *
(my_avcodeccontext_enc->bit_rate/1000000))/1.15) * 8 * 1024;//((40 *
my_avcodeccontext_enc->bit_rate)/1.15) / 1000000.0 * 8 * 1024;
my_avcodeccontext_enc->rc_initial_buffer_occupancy =
(my_avcodeccontext_enc->rc_buffer_size)*3/4;
my_avcodeccontext_enc->me_method = ME_EPZS;
my_avcodeccontext_enc->scenechange_threshold =
1000000000;//-sc_threshold 100000000
my_avcodeccontext_enc->mb_decision = FF_MB_DECISION_RD;//-mbd 2
my_avcodeccontext_enc->lmax = 340*FF_QP2LAMBDA;
my_avcodeccontext_enc->flags |= CODEC_FLAG_CBP_RD;//cbp
my_avcodeccontext_enc->flags |= CODEC_FLAG_TRELLIS_QUANT;//trell
Can anyone help me ?
Thanks in advance,
Tom Douce
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