C++ 使用ffmpeg播放音视频文件

 1、包含必须的头文件。

#include 
extern "C" {
#include 
#include 
#include 
#include 
#include 
}

// SDL相关头文件
#include 
#include 

2、示例。

#define AUDIO_BUFFER_SIZE 4096

typedef struct {
	uint8_t* buffer;
	int size;
	int pos;
} AudioParams;

void audio_callback(void* userdata, Uint8* stream, int len) {
	AudioParams* audioParams = (AudioParams*)userdata;
	if (audioParams->pos >= audioParams->size) {
		return;
	}
	int remaining = audioParams->size - audioParams->pos;
	len = (len > remaining) ? remaining : len;
	memcpy(stream, audioParams->buffer + audioParams->pos, len);
	audioParams->pos += len;
}

int main() {
	AVFormatContext* formatContext = avformat_alloc_context();

	// 打开输入文件
	if (avformat_open_input(&formatContext, "input.mp4", NULL, NULL) != 0) {
		std::cerr << "无法打开输入文件" << std::endl;
		return -1;
	}

	// 检索流信息
	if (avformat_find_stream_info(formatContext, NULL) < 0) {
		std::cerr << "无法检索流信息" << std::endl;
		return -1;
	}

	// 寻找音频流和视频流
	int audioStreamIndex = -1;
	int videoStreamIndex = -1;

	for (unsigned int i = 0; i < formatContext->nb_streams; i++) {
		if (formatContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
			audioStreamIndex = i;
		}
		else if (formatContext->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
			videoStreamIndex = i;
		}
	}

	// 检查是否找到音频流和视频流
	if (audioStreamIndex == -1 || videoStreamIndex == -1) {
		std::cerr << "无法找到音频流或视频流" << std::endl;
		return -1;
	}

	// 获取音频解码器和视频解码器
	AVCodecParameters* audioCodecParameters = formatContext->streams[audioStreamIndex]->codecpar;
	AVCodecParameters* videoCodecParameters = formatContext->streams[videoStreamIndex]->codecpar;

	AVCodec* audioCodec = avcodec_find_decoder(audioCodecParameters->codec_id);
	AVCodec* videoCodec = avcodec_find_decoder(videoCodecParameters->codec_id);

	// 打开音频解码器和视频解码器
	AVCodecContext* audioCodecContext = avcodec_alloc_context3(audioCodec);
	AVCodecContext* videoCodecContext = avcodec_alloc_context3(videoCodec);

	if (!audioCodecContext || !videoCodecContext) {
		std::cerr << "无法分配解码器上下文" << std::endl;
		return -1;
	}

	if (avcodec_parameters_to_context(audioCodecContext, audioCodecParameters) < 0 ||
		avcodec_parameters_to_context(videoCodecContext, videoCodecParameters) < 0) {
		std::cerr << "无法填充解码器上下文" << std::endl;
		return -1;
	}

	if (avcodec_open2(audioCodecContext, audioCodec, NULL) < 0 ||
		avcodec_open2(videoCodecContext, videoCodec, NULL) < 0) {
		std::cerr << "无法打开解码器" << std::endl;
		return -1;
	}

	// 初始化SDL
	if (SDL_Init(SDL_INIT_AUDIO | SDL_INIT_VIDEO) < 0) {
		std::cerr << "无法初始化SDL" << std::endl;
		return -1;
	}

	// 创建窗口和渲染器
	SDL_Window* window = SDL_CreateWindow("Video Player", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED,
		videoCodecParameters->width, videoCodecParameters->height, SDL_WINDOW_SHOWN);
	SDL_Renderer* renderer = SDL_CreateRenderer(window, -1, 0);
	SDL_Texture* texture = SDL_CreateTexture(renderer, SDL_PIXELFORMAT_YV12, SDL_TEXTUREACCESS_STREAMING,
		videoCodecParameters->width, videoCodecParameters->height);

	// 音频参数设置
	AudioParams audioParams;
	audioParams.buffer = new uint8_t[AUDIO_BUFFER_SIZE];
	audioParams.size = AUDIO_BUFFER_SIZE;
	audioParams.pos = 0;

	// 初始化音频重采样上下文
	SwrContext* swrContext = swr_alloc_set_opts(NULL,
		av_get_default_channel_layout(audioCodecContext->channels),
		AV_SAMPLE_FMT_S16,
		audioCodecContext->sample_rate,
		av_get_default_channel_layout(audioCodecContext->channels),
		audioCodecContext->sample_fmt,
		audioCodecContext->sample_rate,
		0, NULL);
	if (!swrContext) {
		std::cerr << "无法分配音频重采样上下文" << std::endl;
		return -1;
	}

	if (swr_init(swrContext) < 0) {
		std::cerr << "无法初始化音频重采样上下文" << std::endl;
		return -1;
	}

	// 打开音频设备
	SDL_AudioSpec desiredSpec, obtainedSpec;
	desiredSpec.freq = audioCodecContext->sample_rate;
	desiredSpec.format = AUDIO_S16SYS;
	desiredSpec.channels = audioCodecContext->channels;
	desiredSpec.silence = 0;
	desiredSpec.samples = 1024;
	desiredSpec.callback = audio_callback;
	desiredSpec.userdata = &audioParams;

	if (SDL_OpenAudio(&desiredSpec, &obtainedSpec) < 0) {
		std::cerr << "无法打开音频设备" << std::endl;
		return -1;
	}

	// 开始播放音频
	SDL_PauseAudio(0);

	// 循环读取帧数据并播放
	AVPacket packet;
	AVFrame* frame = av_frame_alloc();
	AVFrame* convertedFrame = av_frame_alloc();

	while (av_read_frame(formatContext, &packet) >= 0) {
		if (packet.stream_index == audioStreamIndex) {
			// 解码音频帧
			int ret = avcodec_send_packet(audioCodecContext, &packet);

			if (ret < 0) {
				std::cerr << "无法发送音频数据包" << std::endl;
				break;
			}

			while (ret >= 0) {
				ret = avcodec_receive_frame(audioCodecContext, frame);

				if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
					break;
				}
				else if (ret < 0) {
					std::cerr << "无法解码音频帧" << std::endl;
					break;
				}

				// 音频重采样
				int dst_nb_samples = av_rescale_rnd(swr_get_delay(swrContext, frame->sample_rate) +
					frame->nb_samples,
					audioCodecContext->sample_rate,
					frame->sample_rate,
					AV_ROUND_UP);
				av_frame_make_writable(convertedFrame);
				convertedFrame->format = AV_SAMPLE_FMT_S16;
				convertedFrame->channel_layout = audioCodecContext->channel_layout;
				convertedFrame->sample_rate = audioCodecContext->sample_rate;
				convertedFrame->channels = audioCodecContext->channels;
				av_samples_alloc(convertedFrame->data, convertedFrame->linesize, audioCodecContext->channels,
					dst_nb_samples, AV_SAMPLE_FMT_S16, 0);
				swr_convert(swrContext, convertedFrame->data, dst_nb_samples,
					(const uint8_t**)frame->data, frame->nb_samples);

				// 播放音频
				int dataSize = av_get_bytes_per_sample((AVSampleFormat)convertedFrame->format) *
					convertedFrame->nb_samples * convertedFrame->channels;

				if (audioParams.pos + dataSize <= audioParams.size) {
					memcpy(audioParams.buffer + audioParams.pos, convertedFrame->data[0], dataSize);
					audioParams.pos += dataSize;
				}

				av_freep(&convertedFrame->data[0]);
			}
		}
		else if (packet.stream_index == videoStreamIndex) {
			// 解码视频帧
			int ret = avcodec_send_packet(videoCodecContext, &packet);

			if (ret < 0) {
				std::cerr << "无法发送视频数据包" << std::endl;
				// 音频参数设置
				AudioParams audioParams;
				audioParams.buffer = new uint8_t[AUDIO_BUFFER_SIZE];
				audioParams.size = AUDIO_BUFFER_SIZE;
				audioParams.pos = 0;

				// 初始化音频重采样上下文
				SwrContext* swrContext = swr_alloc_set_opts(NULL,
					av_get_default_channel_layout(audioCodecContext->channels),
					AV_SAMPLE_FMT_S16,
					audioCodecContext->sample_rate,
					av_get_default_channel_layout(audioCodecContext->channels),
					audioCodecContext->sample_fmt,
					audioCodecContext->sample_rate,
					0, NULL);
				if (!swrContext) {
					std::cerr << "无法分配音频重采样上下文" << std::endl;
					return -1;
				}

				if (swr_init(swrContext) < 0) {
					std::cerr << "无法初始化音频重采样上下文" << std::endl;
					return -1;
				}

				// 打开音频设备
				SDL_AudioSpec desiredSpec, obtainedSpec;
				desiredSpec.freq = audioCodecContext->sample_rate;
				desiredSpec.format = AUDIO_S16SYS;
				desiredSpec.channels = audioCodecContext->channels;
				desiredSpec.silence = 0;
				desiredSpec.samples = 1024;
				desiredSpec.callback = audio_callback;
				desiredSpec.userdata = &audioParams;

				if (SDL_OpenAudio(&desiredSpec, &obtainedSpec) < 0) {
					std::cerr << "无法打开音频设备" << std::endl;
					return -1;
				}

				// 开始播放音频
				SDL_PauseAudio(0);

				// 循环读取帧数据并播放
				AVPacket packet;
				AVFrame* frame = av_frame_alloc();
				AVFrame* convertedFrame = av_frame_alloc();

				while (av_read_frame(formatContext, &packet) >= 0) {
					if (packet.stream_index == audioStreamIndex) {
						// 解码音频帧
						int ret = avcodec_send_packet(audioCodecContext, &packet);

						if (ret < 0) {
							std::cerr << "无法发送音频数据包" << std::endl;
							break;
						}

						while (ret >= 0) {
							ret = avcodec_receive_frame(audioCodecContext, frame);

							if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
								break;
							}
							else if (ret < 0) {
								std::cerr << "无法解码音频帧" << std::endl;
								break;
							}

							// 音频重采样
							int dst_nb_samples = av_rescale_rnd(swr_get_delay(swrContext, frame->sample_rate) +
								frame->nb_samples,
								audioCodecContext->sample_rate,
								frame->sample_rate,
								AV_ROUND_UP);
							av_frame_make_writable(convertedFrame);
							convertedFrame->format = AV_SAMPLE_FMT_S16;
							convertedFrame->channel_layout = audioCodecContext->channel_layout;
							convertedFrame->sample_rate = audioCodecContext->sample_rate;
							convertedFrame->channels = audioCodecContext->channels;
							av_samples_alloc(convertedFrame->data, convertedFrame->linesize, audioCodecContext->channels,
								dst_nb_samples, AV_SAMPLE_FMT_S16, 0);
							swr_convert(swrContext, convertedFrame->data, dst_nb_samples,
								(const uint8_t**)frame->data, frame->nb_samples);

							// 播放音频
							int dataSize = av_get_bytes_per_sample((AVSampleFormat)convertedFrame->format) *
								convertedFrame->nb_samples * convertedFrame->channels;

							if (audioParams.pos + dataSize <= audioParams.size) {
								memcpy(audioParams.buffer + audioParams.pos, convertedFrame->data[0], dataSize);
								audioParams.pos += dataSize;
							}

							av_freep(&convertedFrame->data[0]);
						}
					}
					else if (packet.stream_index == videoStreamIndex) {
						// 解码视频帧
						int ret = avcodec_send_packet(videoCodecContext, &packet);

						if (ret < 0) {
							std::cerr << "无法发送视频数据包" << std::endl;
							break;
						}
						while (ret >= 0) {
							ret = avcodec_receive_frame(videoCodecContext, frame);

							if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
								break;
							}
							else if (ret < 0) {
								std::cerr << "无法解码视频帧" << std::endl;
								break;
							}

							// 渲染视频
							SDL_UpdateTexture(texture, NULL, frame->data[0], frame->linesize[0]);
							SDL_RenderClear(renderer);
							SDL_RenderCopy(renderer, texture, NULL, NULL);
							SDL_RenderPresent(renderer);
						}
					}

					av_packet_unref(&packet);
				}

				// 释放资源
				av_frame_free(&frame);
				av_frame_free(&convertedFrame);
				avcodec_close(audioCodecContext);
				avcodec_close(videoCodecContext);
				avformat_close_input(&formatContext);
				avformat_free_context(formatContext);
				swr_free(&swrContext);
				SDL_CloseAudio();
				SDL_Quit();

				return 0;
			}
		}
	}
}