ffmpeg AVFrame保存至内存

在ffmpeg中使用AVFrame保存多媒体数据在uint8_t *data[8];但是只有记录数据地址的地方，没有记录数据长度的地方，所有对于需要将data中数据往自定义内存中的时候不方便直接使用memcpy拷贝，需要根据存储格式按规则拷贝。

如对于yuv420p格式存储的数据按如下方式拷贝

unsigned char* data[4] = {0};
int linesize[4] = {0};

linesize[0] = m_frameVideo->linesize[0];
linesize[1] = m_frameVideo->linesize[1];
linesize[2] = m_frameVideo->linesize[2];
linesize[3] = m_frameVideo->linesize[3];

int width = m_frameVideo->width;
int height = m_frameVideo->height;

//Y
for (int i = 0; i < height; i++)
{
    memcpy(data[0] + width * i, m_frameVideo->data[0] + i * m_frameVideo->linesize[0], width);
}
//U
for (int i = 0; i < height / 2; i++)
{
    memcpy(mdata[1] + width / 2 * i, m_frameVideo->data[1] + i * m_frameVideo->linesize[1], width / 2);
}
//V
for (int i = 0; i < height / 2; i++)
{
    memcpy(data[2] + width / 2 * i, m_frameVideo->data[2] + i * m_frameVideo->linesize[2], width / 2);
}

如对于nv12格式存储的数据按如下方式拷贝

​
unsigned char* data[4] = {0};
int linesize[4] = {0};

linesize[0] = m_frameVideo->linesize[0];
linesize[1] = m_frameVideo->linesize[1];
linesize[2] = m_frameVideo->linesize[2];
linesize[3] = m_frameVideo->linesize[3];
//Y
for (int i = 0; i < height; i++)
{
    memcpy(data[0] + width * i, m_frameVideo->data[0] + i * m_videoFrame->m_linesize[0], width);
}
//U/V
for (int i = 0; i < height/2; i++)
{
    memcpy(data[1] + width * i, m_frameVideo->data[1] + i * m_videoFrame->m_linesize[1], width);
}