c++ - FFmpeg 从 H264 比特流中解析 NAL

Question

我可以使用 FFmpeg 将虚拟帧编码为 H264 比特流。我还想做的是从比特流中提取单个 NAL。
从周围的大量狩猎看来，使用 AVParser 和 av_parser_parse2 是这样做的方法吗？我可以在 h264_parser.c 中看到该功能我只是不知道如何连接它。虽然也许 AVparser 只处理帧和 AVBitStreamFilter 还是需要其他东西？
在下面的示例中，我成功编码为 H264 并通过 RTP 传输结果。 ffplay 能够接收并显示它接收到的 H264 RTP 数据包，因此我确信 H264 编码工作正常。

#include <ctime>
#include <iomanip>
#include <iostream>
#include <string>
#include <sstream>

#include "strutils.h"

extern "C"
{
#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libavformat/avio.h>
#include <libavutil/imgutils.h>
#include <libswscale/swscale.h>
#include <libavutil/time.h>
}

#define WIDTH 640
#define HEIGHT 480
#define FRAMES_PER_SECOND 30
#define RTP_OUTPUT_FORMAT "rtp"
#define RTP_URL "rtp://127.0.0.1:5024"
#define ERROR_LEN 128
#define codecID AVCodecID::AV_CODEC_ID_H264 // AVCodecID::AV_CODEC_ID_VP8;

SwsContext* _swsContext;
AVCodec* _codec;
AVCodecContext* _codecCtx;
AVFormatContext* _formatContext;
AVStream* _rtpOutStream;
char _errorLog[ERROR_LEN];
AVCodecParserContext* _codecParserCtx;

int main()
{
  std::cout << "FFmpeg Encoder and RTP Stream Test" << std::endl;

  av_log_set_level(AV_LOG_DEBUG);

  // Initialise codec context.
  _codec = avcodec_find_encoder(codecID);
  if (_codec == NULL) {
    throw std::runtime_error("Could not find codec for ID " + std::to_string(codecID) + ".");
  }

  _codecCtx = avcodec_alloc_context3(_codec);
  if (!_codecCtx) {
    std::cerr << "Failed to initialise codec context." << std::endl;;
  }

  _codecCtx->width = WIDTH;
  _codecCtx->height = HEIGHT;
  //_codecCtx->bit_rate = 500000;
  _codecCtx->time_base.den = FRAMES_PER_SECOND;
  _codecCtx->time_base.num = 1;
  //_codecCtx->gop_size = 10;
  //_codecCtx->max_b_frames = 1;
  _codecCtx->pix_fmt = AVPixelFormat::AV_PIX_FMT_YUV420P;

  int res = avcodec_open2(_codecCtx, _codec, NULL);
  if (res < 0) {
    std::cerr << "Failed to open codec: " << av_make_error_string(_errorLog, ERROR_LEN, res) << std::endl;
  }

  // Set up a parser to extract NAL's from the H264 bit stream.
  // Note this is not needed for sending the RTP (I need to separate the NALs for another reason).
  _codecParserCtx = av_parser_init(codecID);
  if (!_codecParserCtx) {
    std::cerr << "Failed to initialise codec parser." << std::endl;
  }

  // Initialise RTP output stream.
  AVOutputFormat* fmt = av_guess_format(RTP_OUTPUT_FORMAT, NULL, NULL);
  if (!fmt) {
    std::cerr << "Failed to guess output format for " << RTP_OUTPUT_FORMAT << "." << std::endl;
  }

  res = avformat_alloc_output_context2(&_formatContext, fmt, fmt->name, RTP_URL);
  if (res < 0) {
    std::cerr << "Failed to allocate output context: " << av_make_error_string(_errorLog, ERROR_LEN, res) << std::endl;
  }

  _rtpOutStream = avformat_new_stream(_formatContext, _codec);
  if (!_rtpOutStream) {
    std::cerr << "Failed to allocate output stream." << std::endl;
  }

  res = avio_open(&_formatContext->pb, _formatContext->url, AVIO_FLAG_WRITE);
  if (res < 0) {
    std::cerr << "Failed to open RTP output context for writing: " << av_make_error_string(_errorLog, ERROR_LEN, res) << std::endl;
  }

  res = avcodec_parameters_from_context(_rtpOutStream->codecpar, _codecCtx);
  if (res < 0) {
    std::cerr << "Failed to copy codec parameters to stream: " << av_make_error_string(_errorLog, ERROR_LEN, res) << std::endl;
  }

  res = avformat_write_header(_formatContext, NULL);
  if (res < 0) {
    std::cerr << "Failed to write output header: " << av_make_error_string(_errorLog, ERROR_LEN, res) << std::endl;
  }

  av_dump_format(_formatContext, 0, RTP_URL, 1);

  // Set a dummy frame with a YUV420 image.
  AVFrame* frame = av_frame_alloc();
  frame->format = AVPixelFormat::AV_PIX_FMT_YUV420P;
  frame->width = WIDTH;
  frame->height = HEIGHT;
  frame->pts = 0;

  res = av_frame_get_buffer(frame, 0);
  if (res < 0) {
    std::cerr << "Failed on av_frame_get_buffer: " << av_make_error_string(_errorLog, ERROR_LEN, res) << std::endl;
  }

  res = av_frame_make_writable(frame);
  if (res < 0) {
    std::cerr << "Failed on av_frame_make_writable: " << av_make_error_string(_errorLog, ERROR_LEN, res) << std::endl;
  }

  for (int y = 0; y < HEIGHT; y++) {
    for (int x = 0; x < WIDTH; x++) {
      frame->data[0][y * frame->linesize[0] + x] = x + y + 1 * 3;
    }
  }

  for (int y = 0; y < HEIGHT / 2; y++) {
    for (int x = 0; x < WIDTH / 2; x++) {
      frame->data[1][y * frame->linesize[1] + x] = 128 + y + 2;
      frame->data[2][y * frame->linesize[2] + x] = 64 + y + 5;
    }
  }

  std::cout << "press any key to start the stream..." << std::endl;
  getchar();

  // Start the loop to encode the static dummy frame and output on the RTP stream.
  AVPacket* pkt = av_packet_alloc();
  uint8_t* data{ nullptr };
  int dataSize;

  while (true) {
    int sendres = avcodec_send_frame(_codecCtx, frame);
    if (sendres != 0) {
      std::cerr << "avcodec_send_frame error: " << av_make_error_string(_errorLog, ERROR_LEN, sendres) << std::endl;
    }

    // Read encoded packets.
    int ret = 0;
    while (ret >= 0) {

      ret = avcodec_receive_packet(_codecCtx, pkt);

      if (ret == AVERROR(EAGAIN)) {
        // Encoder needs more data.
        break;
      }
      else if (ret < 0) {
        std::cerr << "Failed to encode frame: " << av_make_error_string(_errorLog, ERROR_LEN, sendres) << std::endl;
        break;
      }
      else {
        std::cout << "Encoded packet pts " << pkt->pts << ", size " << pkt->size << "." << std::endl;
        std::cout << toHex(pkt->data, pkt->data + pkt->size) << std::endl;

        int pktOffset = 0;

        // TODO: Find a way to separate the NALs from the Annex B H264 byte stream in the AVPacket data.
        //AVBitStreamFilter 
        
        while (pkt->size > pktOffset) {
          int bytesRead = av_parser_parse2(_codecParserCtx, _codecCtx, &data, &dataSize, pkt->data + pktOffset, pkt->size - pktOffset, AV_NOPTS_VALUE, AV_NOPTS_VALUE, 0);

          if (bytesRead == 0) {
            std::cout << "Failed to parse data from packet." << std::endl;
            break;
          }
          else if (bytesRead < 0) {
            std::cerr << "av_parser_parse2 error: " << av_make_error_string(_errorLog, ERROR_LEN, bytesRead) << std::endl;
            break;
          }
          else {
            std::cout << "Codec parser bytes read " << bytesRead << "." << std::endl;
            pktOffset += bytesRead;
          }
        }
      }

      // Write the encoded packet to the RTP stream.
      int sendRes = av_write_frame(_formatContext, pkt);
      if (sendRes < 0) {
        std::cerr << "Failed to write frame to output stream: " << av_make_error_string(_errorLog, ERROR_LEN, sendres) << std::endl;
        break;
      }

      std::cout << "press any key to continue..." << std::endl;
      getchar();
    }

    av_usleep(1000000 / FRAMES_PER_SECOND);

    frame->pts++;
  }

  av_packet_free(&pkt);
  av_frame_free(&frame);
  avcodec_close(_codecCtx);
  avcodec_free_context(&_codecCtx);
  avformat_free_context(_formatContext);

  return 0;
}

包含 4 个单独 NAL 的第一个可用帧的输出如下(对大小表示歉意)。由于 H264 字节流使用附件 B 格式，因此可以轻松提取 NAL，分隔符为 00000001 或 000001 。如果可能的话，我宁愿使用正确的 FFmpeg 解析方式，而不是重新发明轮子。

FFmpegCppEncodingTest\x64\Debug>FFmpegCppEncodingTest.exe
FFmpeg Encoder and RTP Stream Test
[libx264 @ 00000252de7e2180] using mv_range_thread = 24
[libx264 @ 00000252de7e2180] using cpu capabilities: MMX2 SSE2Fast SSSE3 SSE4.2 AVX FMA3 BMI2 AVX2
[libx264 @ 00000252de7e2180] profile High, level 3.0, 4:2:0, 8-bit
[rtp @ 00000252df9d4c80] No default whitelist set
[udp @ 00000252df9d46c0] No default whitelist set
[udp @ 00000252df501440] No default whitelist set
Output #0, rtp, to 'rtp://127.0.0.1:5024':
  Metadata:
    encoder         : Lavf58.49.100
    Stream #0:0, 0, 1/90000: Video: h264 (libx264), 1 reference frame, yuv420p, 640x480 (0x0), 0/1, q=-1--1, 90k tbn
press any key to start the stream...

[libx264 @ 00000252de7e2180] frame=   0 QP=23.20 NAL=3 Slice:I Poc:0   I:1200 P:0    SKIP:0    size=8262 bytes
Encoded packet pts 0, size 8262.
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
Codec parser bytes read 8262, data size 0.
nal: .
[rtp @ 00000252df4ef8c0] Sending NAL 7 of len 24 M=0
[rtp @ 00000252df4ef8c0] Sending NAL 8 of len 6 M=0
[rtp @ 00000252df4ef8c0] Sending NAL 6 of len 673 M=0
[rtp @ 00000252df4ef8c0] Sending NAL 5 of len 7545 M=1
[rtp @ 00000252df4ef8c0] NAL size 7545 > 1460
press any key to continue...

[libx264 @ 00000252de7e2180] frame=   1 QP=23.21 NAL=2 Slice:P Poc:8   I:52   P:101  SKIP:1047 size=482 bytes
Encoded packet pts 4, size 482.
00000001419a246c45fffa5d37ecc1d1a2448b600952115b6c1b9880c2721414b9ad381385c2d2db0c0fc3041714814ca3fbfc1c85bb5cf888b1442cdf4fd78bed0ff15512df4949c046d5ed117d4ca9c2fe8e16d8b2a0ee8e8ca9ef07d709242427eec2e62e7c5ddd87a9cc7c7fa3c97bcf657971f49b92b8be0b5ec4d9de8d8abe9aa061abf1d193ca02fe38a4c37e5ca55fac90c7e3d20a050d0684cf50614872855915c4e51caffc4e16e50cfee7c2f92c574efd752e2493c2cb07447541446f498625f89c0396f244bd0674dac31a45e98cbdd7f1f447bf8c84b2c288e3693bcfc2c1a4c0789fdce4fa71181f99a2911c044284c0e9c801e9e7417fc7a65a6f02f8482bd969a8776ecbfff27f823c294ed9e28c56c1816d0f40d2c009f83beb246f5f22e39375fae6db239e9d560e8370f61653ec068631bfe84c2ba6376d1435ca231555a828d724ac0a38fc7986b92997c1a18940bc569d2c652b836b6d368c84ff7ebee187f31f84e6289aa7987ffe660ea59897174f5266bbb471b3ec50070d29b08ca8c92b8c2987da5e80448e99667627e55996a00c56753f9fc65fa75d742e5e15d89ecb007496045027a101244ea4f27792ef3210023196008043fa7e1ca05aa3b1e4a8a6ac5e384440cb5d11d9ec2d1117473875947c2f1aacc37c
Failed to parse data from packet.
[rtp @ 00000252df4ef8c0] Sending NAL 1 of len 478 M=1
press any key to continue...

[libx264 @ 00000252de7e2180] frame=   2 QP=26.00 NAL=2 Slice:B Poc:4   I:0    P:102  SKIP:1098 size=91 bytes
Encoded packet pts 2, size 91.
00000001419e42789bff42138e8cab7ce34f0aaf2f3fb0c41aac77dad7803c8a422c3668a09d337695ffad27dd3d2a1499cf8812c8873f3308741b44759e97059270a4f8678646dfa543ae4da163dacc33a85b2694e7e3c052a861
Codec parser bytes read 91, data size 0.
nal: .
[rtp @ 00000252df4ef8c0] Sending NAL 1 of len 87 M=1
press any key to continue...

[libx264 @ 00000252de7e2180] frame=   3 QP=28.00 NAL=0 Slice:B Poc:2   I:0    P:74   SKIP:1126 size=82 bytes
Encoded packet pts 1, size 82.
00000001019e6174457f4a9778ce66461da66e887d240ad470ec49fe325654c49141af33481787c812ab8d6e27331c0203d4fe099ef254623da56868fdac9a5e5f4e08ec8ef08390748186902972dbe37080
Failed to parse data from packet.
[rtp @ 00000252df4ef8c0] Sending NAL 1 of len 78 M=1
press any key to continue...

Answer 1

由于您有兴趣查找由起始代码分隔的 NAL 单元 - 您可以使用 find_start_code https://www.ffmpeg.org/doxygen/trunk/h264dec_8h_source.html#l00822
不导出。所以我可能会将 ffmpeg 代码复制到您的项目中。