LIBAV MJPEG编码和huffman表

Question

我试图使用libav(ffmpeg)示例代码创建带有MJPEG视频有效载荷的RTP流，它对MPEG1非常简单，我看到MJPEG中的编码工作，但是当我需要发送mjpeg帧时，RTP发件人会返回错误：

rtp @000000878ca77a0 RFC 2435需要jpeg的标准Huffman表

我在libav标题中看到了评论：

/**
     * some codecs need / can use extradata like Huffman tables.
     * MJPEG: Huffman tables
     * rv10: additional flags
     * MPEG-4: global headers (they can be in the bitstream or here)
     * The allocated memory should be AV_INPUT_BUFFER_PADDING_SIZE bytes larger
     * than extradata_size to avoid problems if it is read with the bitstream reader.
     * The bytewise contents of extradata must not depend on the architecture or CPU endianness.
     * - encoding: Set/allocated/freed by libavcodec.
     * - decoding: Set/allocated/freed by user.
     */
    uint8_t *extradata;
    int extradata_size;

但是如何更正填充huffman表或init默认表。有我要为编码器设置的标志吗？谢谢。

Answer 1

您可以将huffman选项设置为0，即：

ffmpeg -i /dev/video0 -input_format mjpeg -f v4l2 -pix_fmt yuvj420p -vcodec mjpeg -huffman 0 -f rtp "rtp://127.0.0.1:10000" -sdp_file sdp_file