问题
I have been reading several posts (http://tinyurl.com/nqtfh9a...) and links (http://www.cardinalpeak.com/blog/the-h-264-sequence-parameter-set/) about SPS and PPS, but cannot really get the idea.
I have bought an encoder with a SDK. In the specifications, it gives me this SPS and PPS, and I was wondering if there is any frame rate information here:
SPS= 0x00, 0x00, 0x00, 0x01, 0x67, 0x42, 0x00, 0x1e, 0x9a, 0x74, 0x05, 0x81, 0xec, 0x80
I used an h264 analyzer and I got this information:
Found NAL at offset 4 (0x0004), size 10 (0x000A)
XX 00 00 00 01 67 42 00 1E 9A 74 05 81 EC 80
==================== NAL ====================
forbidden_zero_bit : 0
nal_ref_idc : 3
nal_unit_type : 7 ( Sequence parameter set )
======= SPS =======
profile_idc : 66
constraint_set0_flag : 0
constraint_set1_flag : 0
constraint_set2_flag : 0
constraint_set3_flag : 0
constraint_set4_flag : 0
constraint_set5_flag : 0
reserved_zero_2bits : 0
level_idc : 30
seq_parameter_set_id : 0
chroma_format_idc : 1
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 : 5
pic_order_cnt_type : 0
log2_max_pic_order_cnt_lsb_minus4 : 6
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 : 43
pic_height_in_map_units_minus1 : 29
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 : 0
=== VUI ===
aspect_ratio_info_present_flag : 0
aspect_ratio_idc : 0
sar_width : 0
sar_height : 0
overscan_info_present_flag : 0
overscan_appropriate_flag : 0
video_signal_type_present_flag : 0
video_format : 0
video_full_range_flag : 0
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 : 0
num_units_in_tick : 0
time_scale : 0
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 : 0
motion_vectors_over_pic_boundaries_flag : 0
max_bytes_per_pic_denom : 0
max_bits_per_mb_denom : 0
log2_max_mv_length_horizontal : 0
log2_max_mv_length_vertical : 0
num_reorder_frames : 0
max_dec_frame_buffering : 0
=== HRD ===
cpb_cnt_minus1 : 0
bit_rate_scale : 0
cpb_size_scale : 0
bit_rate_value_minus1[0] : 0
cpb_size_value_minus1[0] : 0
cbr_flag[0] : 0
initial_cpb_removal_delay_length_minus1 : 0
cpb_removal_delay_length_minus1 : 0
dpb_output_delay_length_minus1 : 0
time_offset_length : 0
I have tried to obtain the SPS from this information, but I cannot obtain the same one. Thanks and kind regards
回答1:
It can be conveyed in the SPS, but it's not mandatory. It's in:
SPS -> VUI parameters -> Timing Info
If vui_prameters_present_flag is 1, and timing_info_present_flag is 1, then the two fields you want are: 'num_units_in_tick' and 'time_scale'. The example in your second link has this information.
In the absence of any funny frame rate tricks, and when fixed_frame_rate_flag is 1, then your picture rate (in fps) is: time_scale / num_units_in_tick.
If you are using field-based video then this will be a field rate, so you'll have to halve it to get a frame rate.
来源：https://stackoverflow.com/questions/31334973/find-frame-rate-sps