mediacodec配置h265解码

刺骨的言语ヽ痛彻心扉 2022-05-22 11:13 528阅读 0赞

**参考ffmpeg解析vps，sps和pps：**

在ffmpeg中可以参考下面的函数是如何解析extradata得到vps，sps，pps的：

hevc\_decode\_extradata（）

**AVCodecContext中 extradata 的 parse**

aligned(8) class HEVCDecoderConfigurationRecord
    {
        unsigned int(8) configurationVersion = 1;
        unsigned int(2) general_profile_space;
        unsigned int(1) general_tier_flag;
        unsigned int(5) general_profile_idc;
        unsigned int(32) general_profile_compatibility_flags;
        unsigned int(48) general_constraint_indicator_flags;
        unsigned int(8) general_level_idc;
        bit(4) reserved = ‘1111’b;
        unsigned int(12) min_spatial_segmentation_idc;
        bit(6) reserved = ‘111111’b;
        unsigned int(2) parallelismType;
        bit(6) reserved = ‘111111’b;
        unsigned int(2) chroma_format_idc;
        bit(5) reserved = ‘11111’b;
        unsigned int(3) bit_depth_luma_minus8;
        bit(5) reserved = ‘11111’b;
        unsigned int(3) bit_depth_chroma_minus8;
        bit(16) avgFrameRate;
        bit(2) constantFrameRate;
        bit(3) numTemporalLayers;
        bit(1) temporalIdNested;
        unsigned int(2) lengthSizeMinusOne;
        unsigned int(8) numOfArrays;
        for (j=0; j < numOfArrays; j++)
        {
            bit(1) array_completeness;
            unsigned int(1) reserved = 0;
            unsigned int(6) NAL_unit_type;
            unsigned int(16) numNalus;
            for (i=0; i< numNalus; i++)
            {
                unsigned int(16) nalUnitLength;
                bit(8*nalUnitLength) nalUnit;
            }
        }
    }

**从AVCodecContext读取h265的vps，sps，pps信息**

vps_length = (mCodec->extradata[26] * 256) + mCodec->extradata[27];
            sps_length = (mCodec->extradata[28 + vps_length + 3] * 256) + mCodec->extradata[28 + vps_length + 4]; 
            pps_length = (mCodec->extradata[28 + vps_length + 5 + sps_length + 3] * 256) + mCodec->extradata[28 + vps_length + 5 + sps_length + 4]; 
    
            if ((sps_length > INFO_LENGTH) || (pps_length > INFO_LENGTH)) {
                    ulog_err("UHwDecoderVideo::init failed! sps_length=%d, pps_length=%d, longer than length %d", sps_length, pps_length, INFO_LENGTH);
                    return -1; 
            }   
    
            for (i = 0; i < vps_length; i++) {
                    sps[i] = mCodec->extradata[i + 28];
            }   
            for (i = 0; i < sps_length; i++) {
                    pps[count] = mCodec->extradata[i + 28 + vps_length + 5]; 
                    count++;
            }   
            pps[count++] = 0; pps[count++] = 0; pps[count++] = 0; pps[count++] = 1;
            for (i = 0; i < pps_length; i++) {
                    pps[count] = mCodec->extradata[i + 28 + vps_length + 5 + sps_length + 5]; 
                    count++;
            }   
    
            // print extra data for debug
            //for (i = 0; i < mCodec->extradata_size; i++) {
                    //snprintf(tmp_str, sizeof(tmp_str), "0x%x ", mCodec->extradata[i]);
            for (i = 0; i < vps_length; i++) {
                    snprintf(tmp_str, sizeof(tmp_str), "0x%x ", sps[i]);
                    strncat(extra_str, tmp_str, strlen(tmp_str));
            }   
            //ulog_info("UHwDecoderVideo::init extradata_size=%d, extradata=%s", mCodec->extradata_size, extra_str);
            ulog_info("UHwDecoderVideo::init sps_size=%d, sps=%s", count, extra_str);
            ulog_info("UHwDecoderVideo::init vps_length=%d sps_length=%d, pps_length=%d, count=%d", vps_length, sps_length, pps_length, count);
    
            //init decoder
            //ret = Java_com_youku_uplayer_initDecoder(sps, sps_length, pps, pps_length);
            ret = Java_com_youku_uplayer_initDecoder(sps, vps_length, pps, count);
            if (0 == ret) {
                    mHwThreadIsRunning = true;
            }

Mediacodec

解码h265，mediacodec的接口初始化时，需要在csd-0 buffer中填入vps，sps，pps信息；注意三个参数前都必须加上0，0，0，1的前缀码，后面接着是nalu的两个字节头；