iOS上通过RTMP上的H264videostream
有一点挖掘，我已经find了一个库，从正在写入的.mp4文件中提取NAL单元。 我试图打包这个信息flv通过使用libavformat和libavcodec RTMP。 我使用以下方法设置videostream：
-(void)setupVideoStream { int ret = 0; videoCodec = avcodec_find_decoder(STREAM_VIDEO_CODEC); if (videoCodec == nil) { NSLog(@"Could not find encoder %i", STREAM_VIDEO_CODEC); return; } videoStream = avformat_new_stream(oc, videoCodec); videoCodecContext = videoStream->codec; videoCodecContext->codec_type = AVMEDIA_TYPE_VIDEO; videoCodecContext->codec_id = STREAM_VIDEO_CODEC; videoCodecContext->pix_fmt = AV_PIX_FMT_YUV420P; videoCodecContext->profile = FF_PROFILE_H264_BASELINE; videoCodecContext->bit_rate = 512000; videoCodecContext->bit_rate_tolerance = 0; videoCodecContext->width = STREAM_WIDTH; videoCodecContext->height = STREAM_HEIGHT; videoCodecContext->time_base.den = STREAM_TIME_BASE; videoCodecContext->time_base.num = 1; videoCodecContext->gop_size = STREAM_GOP; videoCodecContext->has_b_frames = 0; videoCodecContext->ticks_per_frame = 2; videoCodecContext->qcompress = 0.6; videoCodecContext->qmax = 51; videoCodecContext->qmin = 10; videoCodecContext->max_qdiff = 4; videoCodecContext->i_quant_factor = 0.71; if (oc->oformat->flags & AVFMT_GLOBALHEADER) videoCodecContext->flags |= CODEC_FLAG_GLOBAL_HEADER; videoCodecContext->extradata = avcCHeader; videoCodecContext->extradata_size = avcCHeaderSize; ret = avcodec_open2(videoStream->codec, videoCodec, NULL); if (ret < 0) NSLog(@"Could not open codec!"); }
然后我连接，并且每次库提取一个NALU时，它都会返回一个包含一个或两个NALU的数组到我的RTMPClient 。 处理实际stream的方法如下所示：
-(void)writeNALUToStream:(NSArray*)data time:(double)pts { int ret = 0; uint8_t *buffer = NULL; int bufferSize = 0; // Number of NALUs within the data array int numNALUs = [data count]; // First NALU NSData *fNALU = [data objectAtIndex:0]; int fLen = [fNALU length]; // If there is more than one NALU... if (numNALUs > 1) { // Second NALU NSData *sNALU = [data objectAtIndex:1]; int sLen = [sNALU length]; // Allocate a buffer the size of first data and second data buffer = av_malloc(fLen + sLen); // Copy the first data bytes of fLen into the buffer memcpy(buffer, [fNALU bytes], fLen); // Copy the second data bytes of sLen into the buffer + fLen + 1 memcpy(buffer + fLen + 1, [sNALU bytes], sLen); // Update the size of the buffer bufferSize = fLen + sLen; }else { // Allocate a buffer the size of first data buffer = av_malloc(fLen); // Copy the first data bytes of fLen into the buffer memcpy(buffer, [fNALU bytes], fLen); // Update the size of the buffer bufferSize = fLen; } // Initialize the packet av_init_packet(&pkt); //av_packet_from_data(&pkt, buffer, bufferSize); // Set the packet data to the buffer pkt.data = buffer; pkt.size = bufferSize; pkt.pts = pts; // Stream index 0 is the video stream pkt.stream_index = 0; // Add a key frame flag every 15 frames if ((processedFrames % 15) == 0) pkt.flags |= AV_PKT_FLAG_KEY; // Write the frame to the stream ret = av_interleaved_write_frame(oc, &pkt); if (ret < 0) NSLog(@"Error writing frame %i to stream", processedFrames); else { // Update the number of frames successfully streamed frameCount++; // Update the number of bytes successfully sent bytesSent += pkt.size; } // Update the number of frames processed processedFrames++; // Update the number of bytes processed processedBytes += pkt.size; free((uint8_t*)buffer); // Free the packet av_free_packet(&pkt); }
大约100帧左右后，我得到一个错误： malloc: *** error for object 0xe5bfa0: incorrect checksum for freed object - object was probably modified after being freed. *** set a breakpoint in malloc_error_break to debug malloc: *** error for object 0xe5bfa0: incorrect checksum for freed object - object was probably modified after being freed. *** set a breakpoint in malloc_error_break to debug
我似乎无法停止发生。 我已经尝试使用av_free_packet()方法和free()以及尝试使用av_packet_from_data()而不是初始化数据包并设置数据和大小值。
我的问题是 我怎么能阻止这个错误发生，根据wireshark，这些都是正确的RTMP h264数据包，但他们不玩什么比黑色屏幕。 我忽略了一些明显的错误吗？
它看起来像你是溢出你的缓冲区和腐败你在这里stream：
memcpy(buffer + fLen + 1, [sNALU bytes], sLen);
您正在分配fLen + sLen字节，然后写入fLen + sLen + 1个字节。 刚刚摆脱了+ 1.
因为你的AVPacket被分配在堆栈上， av_free_packet()是不需要的。 最后，为libav分配额外的字节被认为是很好的做法。 av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE )