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Autres articles (20)
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Qualité du média après traitement
21 juin 2013, parLe bon réglage du logiciel qui traite les média est important pour un équilibre entre les partis ( bande passante de l’hébergeur, qualité du média pour le rédacteur et le visiteur, accessibilité pour le visiteur ). Comment régler la qualité de son média ?
Plus la qualité du média est importante, plus la bande passante sera utilisée. Le visiteur avec une connexion internet à petit débit devra attendre plus longtemps. Inversement plus, la qualité du média est pauvre et donc le média devient dégradé voire (...) -
Websites made with MediaSPIP
2 mai 2011, parThis page lists some websites based on MediaSPIP.
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Creating farms of unique websites
13 avril 2011, parMediaSPIP platforms can be installed as a farm, with a single "core" hosted on a dedicated server and used by multiple websites.
This allows (among other things) : implementation costs to be shared between several different projects / individuals rapid deployment of multiple unique sites creation of groups of like-minded sites, making it possible to browse media in a more controlled and selective environment than the major "open" (...)
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aacenc_is : add a flag to use pure coefficients instead
5 septembre 2015, par Rostislav Pehlivanovaacenc_is : add a flag to use pure coefficients instead
This commit adds a flag to use the pure coefficients instead
of the processed ones (sce->coeffs). This is needed because
IS will apply the changes to the coefficients immediately
before the adjust_common_prediction function and it doesn’t
make sense to measure stereo channel coefficient difference
when one of the channels coefficients are all zero.Therefore add a flag to use pure coefficients in that case.
TNS is the only thing touching the coefficients before IS
so common window prediction will not take that into account
but the effect of the TNS filter per coefficient can be small
(a few percent) so to some approximation it’s fine to just
ignore that.Also fixed a small error which doesn’t alter the results
that much. pow(sqrt(number), 3.0/4.0) == pow(number, 3.0/8.0) !=
pow(number, 3.0/4.0).Signed-off-by : Rostislav Pehlivanov <atomnuker@gmail.com>
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Revision faff6ed0fb : Skip duplicate block encoding in the rd loop This speed feature allows the enco
9 juillet 2013, par Jingning HanChanged Paths :
Modify /vp9/encoder/vp9_block.h
Modify /vp9/encoder/vp9_encodeframe.c
Modify /vp9/encoder/vp9_encodeintra.c
Modify /vp9/encoder/vp9_encodemb.c
Modify /vp9/encoder/vp9_onyx_if.c
Modify /vp9/encoder/vp9_onyx_int.h
Modify /vp9/encoder/vp9_rdopt.c
Modify /vp9/encoder/vp9_rdopt.h
Skip duplicate block encoding in the rd loopThis speed feature allows the encoder to largely remove the spatial
dependency between blocks inside a 64x64 superblock, thereby removing
the need to repeatedly encode superblocks per partition type in the
rate-distortion optimization loop.A major challenge lies in the intra modes tested in the rate-distortion
optimization loop. The subsequent blocks do not have access to the
reconstructed boundary pixels without the intermediate coding steps.
This was resolved by using the original pixels for intra prediction
in the rd loop, followed by an appropriately designed distortion
modeling on the quantization parameters. Experiments also suggested
that the performance impact is more discernible at lower bit-rate/psnr
settings. Hence a quantizer dependent threshold is applied to deactivate
skip of block coding.For bus_cif at 2000 kbps,
speed 0 : runtime 269854ms -> 237774ms (12% speed-up) at 0.05dB
performance loss.speed 1 : runtime 65312ms -> 61536ms, (7% speed-up) at 0.04dB
performance loss.This operation is currently turned on in settings of speed 1.
Change-Id : Ib689741dfff8dd38365d8c1b92860a3e176f56ec
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Libavcodec : How to tell end of access unit when decoding H.264 stream
22 septembre 2011, par FlameI'm receiving H.264 video over RTP and decoding it with libavcodec. I'm unpackaging the NAL units from the RTP packets before feeding them to avcodec (including reassembling fragmentation units).
I'm trying to show effective decoding frame rate. I used to log the time after a successful decode video call where *got_picture_ptr is non-zero. So far this worked since I only ever got video where there was one slice per frame. But now I receive video where both I and P frames consist of 2 NAL units each, of types 5 and 1 respectively. Now when I feed the either slice of a frame, decode_video return that it got a picture, and the pAVFrame->coded_picture_number is increased from every slice.
How do I go about reliably finding the beginning or end of a video frame/picture/access unit ?
I've dumped out a few NAL units from the stream and run them through h264_analyze from h264bitstream.
Output from h264_analyze on 4 NAL Units
!! Found NAL at offset 695262 (0xA9BDE), size 25 (0x0019) ==================== NAL ==================== forbidden_zero_bit : 0 nal_ref_idc : 1 nal_unit_type : 7 ( Sequence parameter set ) ======= SPS ======= profile_idc : 66 constraint_set0_flag : 1 constraint_set1_flag : 1 constraint_set2_flag : 1 constraint_set3_flag : 0 reserved_zero_4bits : 0 level_idc : 32 seq_parameter_set_id : 0 chroma_format_idc : 0 residual_colour_transform_flag : 0 bit_depth_luma_minus8 : 0 bit_depth_chroma_minus8 : 0 qpprime_y_zero_transform_bypass_flag : 0 seq_scaling_matrix_present_flag : 0 log2_max_frame_num_minus4 : 12 pic_order_cnt_type : 2 log2_max_pic_order_cnt_lsb_minus4 : 0 delta_pic_order_always_zero_flag : 0 offset_for_non_ref_pic : 0 offset_for_top_to_bottom_field : 0 num_ref_frames_in_pic_order_cnt_cycle : 0 num_ref_frames : 1 gaps_in_frame_num_value_allowed_flag : 0 pic_width_in_mbs_minus1 : 79 pic_height_in_map_units_minus1 : 44 frame_mbs_only_flag : 1 mb_adaptive_frame_field_flag : 0 direct_8x8_inference_flag : 1 frame_cropping_flag : 0 frame_crop_left_offset : 0 frame_crop_right_offset : 0 frame_crop_top_offset : 0 frame_crop_bottom_offset : 0 vui_parameters_present_flag : 1 === VUI === aspect_ratio_info_present_flag : 1 aspect_ratio_idc : 1 sar_width : 0 sar_height : 0 overscan_info_present_flag : 0 overscan_appropriate_flag : 0 video_signal_type_present_flag : 1 video_format : 5 video_full_range_flag : 1 colour_description_present_flag : 0 colour_primaries : 0 transfer_characteristics : 0 matrix_coefficients : 0 chroma_loc_info_present_flag : 0 chroma_sample_loc_type_top_field : 0 chroma_sample_loc_type_bottom_field : 0 timing_info_present_flag : 1 num_units_in_tick : 1 time_scale : 25 fixed_frame_rate_flag : 0 nal_hrd_parameters_present_flag : 0 vcl_hrd_parameters_present_flag : 0 low_delay_hrd_flag : 0 pic_struct_present_flag : 0 bitstream_restriction_flag : 1 motion_vectors_over_pic_boundaries_flag : 1 max_bytes_per_pic_denom : 0 max_bits_per_mb_denom : 0 log2_max_mv_length_horizontal : 6 log2_max_mv_length_vertical : 6 num_reorder_frames : 0 max_dec_frame_buffering : 1 === HRD === cpb_cnt_minus1 : 0 bit_rate_scale : 0 cpb_size_scale : 0 initial_cpb_removal_delay_length_minus1 : 0 cpb_removal_delay_length_minus1 : 0 dpb_output_delay_length_minus1 : 0 time_offset_length : 0 !! Found NAL at offset 695290 (0xA9BFA), size 4 (0x0004) ==================== NAL ==================== forbidden_zero_bit : 0 nal_ref_idc : 1 nal_unit_type : 8 ( Picture parameter set ) ======= PPS ======= pic_parameter_set_id : 0 seq_parameter_set_id : 0 entropy_coding_mode_flag : 0 pic_order_present_flag : 0 num_slice_groups_minus1 : 0 slice_group_map_type : 0 num_ref_idx_l0_active_minus1 : 0 num_ref_idx_l1_active_minus1 : 0 weighted_pred_flag : 0 weighted_bipred_idc : 0 pic_init_qp_minus26 : 3 pic_init_qs_minus26 : 0 chroma_qp_index_offset : 0 deblocking_filter_control_present_flag : 1 constrained_intra_pred_flag : 0 redundant_pic_cnt_present_flag : 0 transform_8x8_mode_flag : 1 pic_scaling_matrix_present_flag : 0 second_chroma_qp_index_offset : 1 !! Found NAL at offset 695297 (0xA9C01), size 50725 (0xC625) ==================== NAL ==================== forbidden_zero_bit : 0 nal_ref_idc : 1 nal_unit_type : 5 ( Coded slice of an IDR picture ) ======= Slice Header ======= first_mb_in_slice : 0 slice_type : 2 ( I slice ) pic_parameter_set_id : 0 frame_num : 0 field_pic_flag : 0 bottom_field_flag : 0 idr_pic_id : 0 pic_order_cnt_lsb : 0 delta_pic_order_cnt_bottom : 0 redundant_pic_cnt : 0 direct_spatial_mv_pred_flag : 0 num_ref_idx_active_override_flag : 0 num_ref_idx_l0_active_minus1 : 0 num_ref_idx_l1_active_minus1 : 0 cabac_init_idc : 0 slice_qp_delta : 5 sp_for_switch_flag : 0 slice_qs_delta : 0 disable_deblocking_filter_idc : 0 slice_alpha_c0_offset_div2 : 0 slice_beta_offset_div2 : 0 slice_group_change_cycle : 0 === Prediction Weight Table === luma_log2_weight_denom : 0 chroma_log2_weight_denom : 0 luma_weight_l0_flag : 0 chroma_weight_l0_flag : 0 luma_weight_l1_flag : 0 chroma_weight_l1_flag : 0 === Ref Pic List Reordering === ref_pic_list_reordering_flag_l0 : 0 ref_pic_list_reordering_flag_l1 : 0 === Decoded Ref Pic Marking === no_output_of_prior_pics_flag : 0 long_term_reference_flag : 0 adaptive_ref_pic_marking_mode_flag : 0 !! Found NAL at offset 746025 (0xB6229), size 38612 (0x96D4) ==================== NAL ==================== forbidden_zero_bit : 0 nal_ref_idc : 1 nal_unit_type : 5 ( Coded slice of an IDR picture ) ======= Slice Header ======= first_mb_in_slice : 1840 slice_type : 2 ( I slice ) pic_parameter_set_id : 0 frame_num : 0 field_pic_flag : 0 bottom_field_flag : 0 idr_pic_id : 0 pic_order_cnt_lsb : 0 delta_pic_order_cnt_bottom : 0 redundant_pic_cnt : 0 direct_spatial_mv_pred_flag : 0 num_ref_idx_active_override_flag : 0 num_ref_idx_l0_active_minus1 : 0 num_ref_idx_l1_active_minus1 : 0 cabac_init_idc : 0 slice_qp_delta : 5 sp_for_switch_flag : 0 slice_qs_delta : 0 disable_deblocking_filter_idc : 0 slice_alpha_c0_offset_div2 : 0 slice_beta_offset_div2 : 0 slice_group_change_cycle : 0 === Prediction Weight Table === luma_log2_weight_denom : 0 chroma_log2_weight_denom : 0 luma_weight_l0_flag : 0 chroma_weight_l0_flag : 0 luma_weight_l1_flag : 0 chroma_weight_l1_flag : 0 === Ref Pic List Reordering === ref_pic_list_reordering_flag_l0 : 0 ref_pic_list_reordering_flag_l1 : 0 === Decoded Ref Pic Marking === no_output_of_prior_pics_flag : 0 long_term_reference_flag : 0 adaptive_ref_pic_marking_mode_flag : 0Both I slices show the frame_num = 0. The next 2 (not shown) have frame_num = 1.
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