MediaCodec C++将MP4文件解码为YUV格式例子

这里有一个简单的MediaCodec C++例子，可以将MP4文件解码为YUV格式：

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <media/NdkMediaCodec.h>
#include <media/NdkMediaExtractor.h>
#include <media/NdkMediaFormat.h>

#define TIMEOUT_US 10000

int main(int argc, char **argv) {
    if (argc != 3) {
        fprintf(stderr, "Usage: %s <input.mp4> <output.yuv>\n", argv[0]);
        return -1;
    }

    // 创建MediaExtractor对象
    AMediaExtractor *extractor = AMediaExtractor_new();
    if (!extractor) {
        fprintf(stderr, "Failed to create MediaExtractor\n");
        return -1;
    }

    // 设置数据源
    if (AMediaExtractor_setDataSource(extractor, argv[1]) != AMEDIA_OK) {
        fprintf(stderr, "Failed to set data source '%s'\n", argv[1]);
        return -1;
    }

    // 获取视频轨道
    AMediaFormat *format = NULL;
    int trackIndex = -1;
    for (int i = 0; i < AMediaExtractor_getTrackCount(extractor); i++) {
        format = AMediaExtractor_getTrackFormat(extractor, i);
        const char *mime;
        AMediaFormat_getString(format, AMEDIAFORMAT_KEY_MIME, &mime);
        if (!strncmp(mime, "video/", 6)) {
            trackIndex = i;
            break;
        }
    }
    if (trackIndex == -1) {
        fprintf(stderr, "No video track found\n");
        return -1;
    }

    // 选择视频轨道
    AMediaExtractor_selectTrack(extractor, trackIndex);

    // 创建MediaCodec对象
    AMediaCodec *decoder = AMediaCodec_createDecoderByType(AMediaFormat_toString(format));
    if (!decoder) {
        fprintf(stderr, "Failed to create decoder for '%s'\n", AMediaFormat_toString(format));
        return -1;
    }

    // 配置MediaCodec对象
    AMediaCodec_configure(decoder, format, NULL, NULL, 0);

    // 启动MediaCodec对象
    AMediaCodec_start(decoder);

    // 创建输出文件
    FILE *fpOut = fopen(argv[2], "wb");
    if (!fpOut) {
        fprintf(stderr, "Failed to create output file '%s'\n", argv[2]);
        return -1;
    }

    // 解码视频数据
    ssize_t sampleSize = 0;
    uint8_t *inputBuffer = NULL;
    size_t inputBufferSize = 0;
    AMediaCodecBufferInfo inputBufferInfo;
    memset(&inputBufferInfo, 0, sizeof(inputBufferInfo));
    bool sawInputEOS = false;
    bool sawOutputEOS = false;
    while (!sawOutputEOS) {
        // 从Extractor中获取输入数据
        if (!sawInputEOS) {
            int inputBufferIndex = AMediaCodec_dequeueInputBuffer(decoder, TIMEOUT_US);
            if (inputBufferIndex >= 0) {
                inputBuffer = AMediaCodec_getInputBuffer(decoder, inputBufferIndex, &inputBufferSize);
                sampleSize = AMediaExtractor_readSampleData(extractor, inputBuffer, inputBufferSize);
                if (sampleSize < 0) {
                    // 输入结束，发送EOS标志
                    AMediaCodec_queueInputBuffer(decoder, inputBufferIndex, 0, 0, 0, AMEDIACODEC_BUFFER_FLAG_END_OF_STREAM);
                    sawInputEOS = true;
                } else {
                    // 将数据提交给MediaCodec对象进行解码
                    AMediaCodec_queueInputBuffer(decoder, inputBufferIndex, 0, sampleSize, AMediaExtractor_getSampleTime(extractor), 0);
                    AMediaExtractor_advance(extractor);
                }
            }
        }

        // 从MediaCodec中获取输出数据
        AMediaCodecBufferInfo outputBufferInfo;
        uint8_t *outputBuffer = AMediaCodec_getOutputBuffer(decoder, &outputBufferInfo, TIMEOUT_US);
        if (outputBuffer) {
            // 将YUV数据保存到文件中
            fwrite(outputBuffer, 1, outputBufferInfo.size, fpOut);
            // 释放输出缓冲区
            AMediaCodec_releaseOutputBuffer(decoder, AMEDIACODEC_INFO_OUTPUT_BUFFERS_CHANGED, false);
            if ((outputBufferInfo.flags & AMEDIACODEC_BUFFER_FLAG_END_OF_STREAM) != 0) {
                sawOutputEOS = true;
            }
        } else if (outputBuffer == NULL && sawInputEOS) {
            break;
        }
    }

    // 关闭输出文件
    fclose(fpOut);

    // 停止并释放MediaCodec对象
    AMediaCodec_stop(decoder);
    AMediaCodec_delete(decoder);

    // 释放MediaExtractor对象
    AMediaExtractor_delete(extractor);

    return 0;
}

请注意，此示例仅用于演示如何使用MediaCodec C++将MP4文件解码为YUV格式。实际应用中，您需要根据您的具体需求进行适当的修改和优化。