基于ffmpeg实现硬件解码功能

#include <stdio.h> #include "FFmpegHWDecodeSample.h" static AVBufferRef* hw_device_ctx = NULL; static enum AVPixelFormat hw_pix_fmt; static FILE* output_file = NULL; /// 硬件加速初始化 static int hw_decoder_init(AVCodecContext* ctx, const enum AVHWDeviceType type) { int err = 0; /// 创建一个硬件设备上下文 if ((err = av_hwdevice_ctx_create(&hw_device_ctx, type, NULL, NULL, 0)) < 0) { fprintf(stderr, "Failed to create specified HW device.\n"); return err; } ctx->hw_device_ctx = av_buffer_ref(hw_device_ctx); return err; } /// 获取GPU硬件解码帧的格式 static enum AVPixelFormat get_hw_format(AVCodecContext* ctx, const enum AVPixelFormat* pix_fmts) { const enum AVPixelFormat* p; for (p = pix_fmts; *p != -1; p++) { if (*p == hw_pix_fmt) return *p; } fprintf(stderr, "Failed to get HW surface format.\n"); return AV_PIX_FMT_NONE; } /// 解码后数据格式转换，GPU到CPU拷贝，YUV数据dump到文件 static int decode_write(AVCodecContext* avctx, AVPacket* packet) { AVFrame* frame = NULL, * sw_frame = NULL; AVFrame* tmp_frame = NULL; uint8_t* buffer = NULL; int size; int ret = 0; ret = avcodec_send_packet(avctx, packet); if (ret < 0) { fprintf(stderr, "Error during decoding\n"); return ret; } while (1) { if (!(frame = av_frame_alloc()) || !(sw_frame = av_frame_alloc())) { fprintf(stderr, "Can not alloc frame\n"); ret = AVERROR(ENOMEM); goto fail; } ret = avcodec_receive_frame(avctx, frame); if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) { av_frame_free(&frame); av_frame_free(&sw_frame); return 0; } else if (ret < 0) { fprintf(stderr, "Error while decoding\n"); goto fail; } if (frame->format == hw_pix_fmt) { /// 将解码后的数据从GPU内存存格式转为CPU内存格式，并完成GPU到CPU内存的拷贝 if ((ret = av_hwframe_transfer_data(sw_frame, frame, 0)) < 0) { fprintf(stderr, "Error transferring the data to system memory\n"); goto fail; } tmp_frame = sw_frame; } else tmp_frame = frame; ///计算一张YUV图需要的内存 大小 size = av_image_get_buffer_size((AVPixelFormat)tmp_frame->format, tmp_frame->width, tmp_frame->height, 1); ///分配内存 buffer = (uint8_t *)av_malloc(size); if (!buffer) { fprintf(stderr, "Can not alloc buffer\n"); ret = AVERROR(ENOMEM); goto fail; } ///将图片数据拷贝的buffer中(按行拷贝) ret = av_image_copy_to_buffer(buffer, size, (const uint8_t* const*)tmp_frame->data, (const int*)tmp_frame->linesize, (AVPixelFormat)tmp_frame->format, tmp_frame->width, tmp_frame->height, 1); if (ret < 0) { fprintf(stderr, "Can not copy image to buffer\n"); goto fail; } ///buffer数据dump到文件 if ((ret = fwrite(buffer, 1, size, output_file)) < 0) { fprintf(stderr, "Failed to dump raw data.\n"); goto fail; } fail: av_frame_free(&frame); av_frame_free(&sw_frame); av_freep(&buffer); if (ret < 0) return ret; } } int main(int argc,char * argv[]) { AVFormatContext* input_ctx = NULL; int video_stream, ret; AVStream* video = NULL; AVCodecContext* decoder_ctx = NULL; AVCodec* decoder = NULL; AVPacket packet; enum AVHWDeviceType type; int i; if (argc < 4) { fprintf(stderr, "Usage: %s <device type> <input file> <output file>\n", argv[0]); return -1; } /// 设备类型为：cuda dxva2 qsv d3d11va opencl，通常在windows使用d3d11va或者dxva2 type = av_hwdevice_find_type_by_name(argv[1]); ///根据设备名找到设备类型 if (type == AV_HWDEVICE_TYPE_NONE) { fprintf(stderr, "Device type %s is not supported.\n", argv[1]); fprintf(stderr, "Available device types:"); while ((type = av_hwdevice_iterate_types(type)) != AV_HWDEVICE_TYPE_NONE) fprintf(stderr, " %s", av_hwdevice_get_type_name(type)); fprintf(stderr, "\n"); return -1; } /// open the input file if (avformat_open_input(&input_ctx, argv[2], NULL, NULL) != 0) { fprintf(stderr, "Cannot open input file '%s'\n", argv[2]); return -1; } if (avformat_find_stream_info(input_ctx, NULL) < 0) { fprintf(stderr, "Cannot find input stream information.\n"); return -1; } /// find the video stream information ret = av_find_best_stream(input_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, &decoder, 0); if (ret < 0) { fprintf(stderr, "Cannot find a video stream in the input file\n"); return -1; } video_stream = ret; ///查找到对应硬件类型解码后的数据格式 for (i = 0;; i++) { const AVCodecHWConfig* config = avcodec_get_hw_config(decoder, i); if (!config) { fprintf(stderr, "Decoder %s does not support device type %s.\n", decoder->name, av_hwdevice_get_type_name(type)); return -1; } if (config->methods & AV_CODEC_HW_CONFIG_METHOD_HW_DEVICE_CTX && config->device_type == type) { hw_pix_fmt = config->pix_fmt; break; } } if (!(decoder_ctx = avcodec_alloc_context3(decoder))) return AVERROR(ENOMEM); video = input_ctx->streams[video_stream]; if (avcodec_parameters_to_context(decoder_ctx, video->codecpar) < 0) return -1; decoder_ctx->get_format = get_hw_format; ///硬件加速初始化 if (hw_decoder_init(decoder_ctx, type) < 0) return -1; if ((ret = avcodec_open2(decoder_ctx, decoder, NULL)) < 0) { fprintf(stderr, "Failed to open codec for stream #%u\n", video_stream); return -1; } /// open the file to dump raw data output_file = fopen(argv[3], "w+b"); /// actual decoding and dump the raw data while (ret >= 0) { if ((ret = av_read_frame(input_ctx, &packet)) < 0) break; if (video_stream == packet.stream_index) ret = decode_write(decoder_ctx, &packet); ///解码并dump文件 av_packet_unref(&packet); } /// flush the decoder packet.data = NULL; packet.size = 0; ret = decode_write(decoder_ctx, &packet); av_packet_unref(&packet); if (output_file) fclose(output_file); avcodec_free_context(&decoder_ctx); avformat_close_input(&input_ctx); av_buffer_unref(&hw_device_ctx); return 0; }