代码已经过测试，能正确获取宽高。
SPS数据是完整的，没有去掉头。如果要去掉，注意NAL_HEADER即可。测试时应该是：0, 0, 0, 1, 0x67, 0x42。。。
JAVA版
package net.quantum6.mediacodec; import net.quantum6.kit.Log; public class H264SpsParser { private final static String TAG = H264SpsParser.class.getCanonicalName(); private final static int NAL_HEADER = 4; private static int nStartBit = 0; private static int Ue(byte[] pBuff, int nLen) { int nZeroNum = 0; while (nStartBit < nLen * 8) { if ((pBuff[nStartBit / 8] & (0x80 >> (nStartBit % 8))) != 0) { break; } nZeroNum++; nStartBit++; } nStartBit ++; int dwRet = 0; for (int i=0; i<nZeroNum; i++) { dwRet <<= 1; if ((pBuff[nStartBit / 8] & (0x80 >> (nStartBit % 8))) != 0) { dwRet += 1; } nStartBit++; } return (1 << nZeroNum) - 1 + dwRet; } private static int Se(byte[] pBuff, int nLen) { int UeVal =Ue(pBuff,nLen); double k =UeVal; int nValue=(int)Math.ceil(k/2); if (UeVal % 2==0) { nValue=-nValue; } return nValue; } private static int u(int BitCount, byte[] buf) { int dwRet = 0; for (int i=0; i<BitCount; i++) { dwRet <<= 1; if ((buf[nStartBit / 8] & (0x80 >> (nStartBit % 8))) != 0) { dwRet += 1; } nStartBit++; } return dwRet; } private static boolean h264_decode_seq_parameter_set(byte[] buf, int nLen, int[] size) { nStartBit = NAL_HEADER*8; int forbidden_zero_bit=u(1, buf); int nal_ref_idc =u(2, buf); int nal_unit_type =u(5, buf); if(nal_unit_type==7) { int profile_idc =u(8, buf); int constraint_set0_flag=u(1, buf);//(buf[1] & 0x80)>>7; int constraint_set1_flag=u(1, buf);//(buf[1] & 0x40)>>6; int constraint_set2_flag=u(1, buf);//(buf[1] & 0x20)>>5; int constraint_set3_flag=u(1, buf);//(buf[1] & 0x10)>>4; int reserved_zero_4bits =u(4, buf); int level_idc =u(8, buf); int seq_parameter_set_id=Ue(buf, nLen); if ( profile_idc == 100 || profile_idc == 110 || profile_idc == 122 || profile_idc == 144 ) { int chroma_format_idc=Ue(buf, nLen); if ( chroma_format_idc == 3 ) { int residual_colour_transform_flag=u(1,buf); } int bit_depth_luma_minus8 =Ue(buf, nLen); int bit_depth_chroma_minus8 =Ue(buf, nLen); int qpprime_y_zero_transform_bypass_flag=u(1, buf); int seq_scaling_matrix_present_flag =u(1, buf); int[] seq_scaling_list_present_flag = new int[8]; if ( seq_scaling_matrix_present_flag != 0) { for( int i = 0; i < 8; i++ ) { seq_scaling_list_present_flag[i]=u(1, buf); } } } int log2_max_frame_num_minus4=Ue(buf, nLen); int pic_order_cnt_type =Ue(buf, nLen); if ( pic_order_cnt_type == 0 ) { int log2_max_pic_order_cnt_lsb_minus4=Ue(buf, nLen); } else if( pic_order_cnt_type == 1 ) { int delta_pic_order_always_zero_flag =u(1, buf); int offset_for_non_ref_pic =Se(buf, nLen); int offset_for_top_to_bottom_field =Se(buf, nLen); int num_ref_frames_in_pic_order_cnt_cycle=Ue(buf, nLen); int[] offset_for_ref_frame=new int[num_ref_frames_in_pic_order_cnt_cycle]; for( int i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; i++ ) { offset_for_ref_frame[i]=Se(buf, nLen); } } int num_ref_frames =Ue(buf, nLen); int gaps_in_frame_num_value_allowed_flag=u(1, buf); int pic_width_in_mbs_minus1 =Ue(buf, nLen); int pic_height_in_map_units_minus1 =Ue(buf, nLen); size[0]=(pic_width_in_mbs_minus1 +1)*16; size[1]=(pic_height_in_map_units_minus1+1)*16; /* int frame_mbs_only_flag=u(1,buf,StartBit); if(!frame_mbs_only_flag) int mb_adaptive_frame_field_flag=u(1,buf,StartBit); int direct_8x8_inference_flag=u(1,buf,StartBit); int frame_cropping_flag=u(1,buf,StartBit); if(frame_cropping_flag) { int frame_crop_left_offset=Ue(buf,nLen,StartBit); int frame_crop_right_offset=Ue(buf,nLen,StartBit); int frame_crop_top_offset=Ue(buf,nLen,StartBit); int frame_crop_bottom_offset=Ue(buf,nLen,StartBit); } int vui_parameter_present_flag=u(1,buf,StartBit); if(vui_parameter_present_flag) { int aspect_ratio_info_present_flag=u(1,buf,StartBit); if(aspect_ratio_info_present_flag) { int aspect_ratio_idc=u(8,buf,StartBit); if(aspect_ratio_idc==255) { int sar_width=u(16,buf,StartBit); int sar_height=u(16,buf,StartBit); } } int overscan_info_present_flag=u(1,buf,StartBit); if(overscan_info_present_flag) int overscan_appropriate_flagu=u(1,buf,StartBit); int video_signal_type_present_flag=u(1,buf,StartBit); if(video_signal_type_present_flag) { int video_format=u(3,buf,StartBit); int video_full_range_flag=u(1,buf,StartBit); int colour_description_present_flag=u(1,buf,StartBit); if(colour_description_present_flag) { int colour_primaries=u(8,buf,StartBit); int transfer_characteristics=u(8,buf,StartBit); int matrix_coefficients=u(8,buf,StartBit); } } int chroma_loc_info_present_flag=u(1,buf,StartBit); if(chroma_loc_info_present_flag) { int chroma_sample_loc_type_top_field=Ue(buf,nLen,StartBit); int chroma_sample_loc_type_bottom_field=Ue(buf,nLen,StartBit); } int timing_info_present_flag=u(1,buf,StartBit); if(timing_info_present_flag) { int num_units_in_tick=u(32,buf,StartBit); int time_scale=u(32,buf,StartBit); fps=time_scale/num_units_in_tick; int fixed_frame_rate_flag=u(1,buf,StartBit); if(fixed_frame_rate_flag) { fps=fps/2; } } } */ return true; } return false; } public static int[] getSizeFromSps(byte[] data) { for (int i=0; i<data.length-4; i++) { if (data[i]==0 && data[i+1]==0 && data[i+2]==0 && data[i+3]==1 && data[i+4]==0x67) { int[] size = new int[2]; h264_decode_seq_parameter_set(data, data.length, size); Log.d(TAG, "Sps=("+size[0]+", "+size[1]+")"); return size; } } return null; } }
C版
JAVA代码是从C改过来的。没有运行。也许有小错误，各位参考JAVA再改。
#include <cstdint> #include <cmath> #define NAL_HEADEER 4 uint32_t Ue(uint8_t *pBuff, uint32_t nLen, uint32_t &nStartBit) { //计算0bit的个数 uint32_t nZeroNum = 0; while (nStartBit < nLen * 8) { if (pBuff[nStartBit / 8] & (0x80 >> (nStartBit % 8))) //&:按位与，%取余 { break; } nZeroNum++; nStartBit++; } nStartBit ++; //计算结果 uint32_t dwRet = 0; for (uint32_t i=0; i<nZeroNum; i++) { dwRet <<= 1; if (pBuff[nStartBit / 8] & (0x80 >> (nStartBit % 8))) { dwRet += 1; } nStartBit++; } return (1 << nZeroNum) - 1 + dwRet; } int Se(uint8_t *pBuff, uint32_t nLen, uint32_t &nStartBit) { int UeVal=Ue(pBuff,nLen,nStartBit); double k=UeVal; int nValue=ceil(k/2);//ceil函数：ceil函数的作用是求不小于给定实数的最小整数。ceil(2)=ceil(1.2)=cei(1.5)=2.00 if (UeVal % 2==0) { nValue=-nValue; } return nValue; } uint32_t u(uint32_t BitCount, uint8_t * buf, uint32_t &nStartBit) { uint32_t dwRet = 0; for (uint32_t i=0; i<BitCount; i++) { dwRet <<= 1; if (buf[nStartBit / 8] & (0x80 >> (nStartBit % 8))) { dwRet += 1; } nStartBit++; } return dwRet; } bool h264_decode_seq_parameter_set(uint8_t * buf, uint32_t nLen ,int &Width, int &Height) { uint32_t StartBit=NAL_HEADEER*8; int forbidden_zero_bit=u(1, buf, StartBit); int nal_ref_idc =u(2, buf, StartBit); int nal_unit_type =u(5, buf, StartBit); if (nal_unit_type==7) { int profile_idc =u(8, buf, StartBit); int constraint_set0_flag=u(1, buf, StartBit);//(buf[1] & 0x80)>>7; int constraint_set1_flag=u(1, buf, StartBit);//(buf[1] & 0x40)>>6; int constraint_set2_flag=u(1, buf, StartBit);//(buf[1] & 0x20)>>5; int constraint_set3_flag=u(1, buf, StartBit);//(buf[1] & 0x10)>>4; int reserved_zero_4bits =u(4, buf, StartBit); int level_idc=u(8, buf, StartBit); int seq_parameter_set_id=Ue(buf, nLen, StartBit); if ( profile_idc == 100 || profile_idc == 110 || profile_idc == 122 || profile_idc == 144 ) { int chroma_format_idc=Ue(buf, nLen, StartBit); if ( chroma_format_idc == 3 ) { int residual_colour_transform_flag =u(1, buf, StartBit); } int bit_depth_luma_minus8 =Ue(buf, nLen, StartBit); int bit_depth_chroma_minus8 =Ue(buf, nLen, StartBit); int qpprime_y_zero_transform_bypass_flag=u(1, buf, StartBit); int seq_scaling_matrix_present_flag =u(1, buf, StartBit); int seq_scaling_list_present_flag[8]; if ( seq_scaling_matrix_present_flag ) { for ( int i = 0; i < 8; i++ ) { seq_scaling_list_present_flag[i]=u(1, buf, StartBit); } } } int log2_max_frame_num_minus4=Ue(buf, nLen, StartBit); int pic_order_cnt_type =Ue(buf, nLen, StartBit); if ( pic_order_cnt_type == 0 ) { int log2_max_pic_order_cnt_lsb_minus4=Ue(buf, nLen, StartBit); } else if ( pic_order_cnt_type == 1 ) { int delta_pic_order_always_zero_flag =u(1, buf, StartBit); int offset_for_non_ref_pic =Se(buf, nLen, StartBit); int offset_for_top_to_bottom_field =Se(buf, nLen, StartBit); int num_ref_frames_in_pic_order_cnt_cycle=Ue(buf, nLen, StartBit); int *offset_for_ref_frame=new int[num_ref_frames_in_pic_order_cnt_cycle]; for ( int i = 0; i < num_ref_frames_in_pic_order_cnt_cycle; i++ ) { offset_for_ref_frame[i]=Se(buf, nLen, StartBit); } delete [] offset_for_ref_frame; } int num_ref_frames=Ue(buf,nLen,StartBit); int gaps_in_frame_num_value_allowed_flag=u(1, buf, StartBit); int pic_width_in_mbs_minus1 =Ue(buf, nLen, StartBit); int pic_height_in_map_units_minus1 =Ue(buf, nLen, StartBit); Width =(pic_width_in_mbs_minus1 +1)*16; Height=(pic_height_in_map_units_minus1+1)*16; return true; } return false; } int main() { int Width, Height; if (h264_decode_seq_parameter_set(str, 11, Width, Height)) { } return 0; }
