【FFmpeg解码实战】（2）分离视频文件中的视频流每一张图片（进阶）（C）

【FFmpeg编程实战】（2）分离视频文件中的视频流每一张图片（进阶）（C）

一、代码修改二、运行结果三、完整代码

在前文《【FFmpeg解码实战】（1）分离视频文件中的音频流和视频流》中， 我们实现了对视频的解复用功能，以MP4为例，解复用后为 H264视频流 和 AAC音频流。

本文在前文的基础上，来实现将前面的代码修改为不保存H264文件，而是保存成一张一张的yuv420p图片。

本文VS2019项目工程所有文件已打包上传到，欢迎下载：《VS2019-解码视频-工程所有文件.zip》， 注意工程中需要配置ffmpeg 的lib库路径及头文件路径才可使用

本文链接：《【FFmpeg解码实战】（2）分离视频文件中的视频流每一张图片（进阶）（C）》

一、代码修改

其实很简闲单，修改的地方也不多，如下: 在保存 h264 video 视频流时，分开来，保存成 video/Video_Test_out.yuv420p.0.yuv ， 图片名字，根据 video_frame_count++ 的自加而变化。

#define YUV420P_FILE 1 // 视频流保存成 yuv420p 图片 //#define H264_FILE 1 // 视频流保存成 H264 文件 #ifdef H264_FILE sprintf_s(video_dst_filename, 50, "%s.%s", "Video_Test_out", video_dec->name); ret = fopen_s(&video_dst_file, video_dst_filename, "wb"); printf("open file:%s ret:%d\n", video_dst_filename, ret); #endif while (av_read_frame(fmt_ctx, &pkt) >= 0) { // 10. 视频数据解码 if (pkt.stream_index == video_stream_idx) { ...... #ifdef YUV420P_FILE // 10.4 写入文件 sprintf_s(video_dst_filename, 50, "video/%s.%s.%d.yuv", "Video_Test_out", av_get_pix_fmt_name(video_dec_ctx->pix_fmt), video_frame_count++); ret = fopen_s(&video_dst_file, video_dst_filename, "wb"); //printf("open file:%s ret:%d\n", video_dst_filename, ret); #endif ret = (int)fwrite(video_dst_data[0], 1, video_dst_bufsize, video_dst_file); //printf("Write Size:%d\n", ret); #ifdef YUV420P_FILE fclose(video_dst_file); #endif } ...... } ...... #ifdef H264_FILE fclose(video_dst_file); #endif

二、运行结果

Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Video_Test.mp4': Metadata: major_brand : isom minor_version : 512 compatible_brands: isomiso2avc1mp41 Duration: 00:02:45.92, start: 0.000000, bitrate: 1076 kb/s Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 975 kb/s, 24.98 fps, 25 tbr, 12800 tbn, 50 tbc (default) Metadata: handler_name : VideoHandler Stream #0:1(und): Audio: aac (HE-AAC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 96 kb/s (default) Metadata: handler_name : SoundHandler #===> Find video_stream_idx = 0 #===> Find decoder: h264, coded_id:27 long name: H.264 / AVC / MPEG-4 AVC / MPEG-4 part 10 pix_fmt=0 (yuv420p) #===> Find audio_stream_idx = 1 #===> Find decoder: aac, coded_id:86018 long name: AAC (Advanced Audio Coding) open file:Video_Test_out.aac ret:0 Start read frame Demuxing succeeded. Play the output video file with the command: ffplay -f rawvideo -pix_fmt yuv420p -video_size 1280x720 video/Video_Test_out.yuv420p.4139.yuv Warning: the sample format the decoder produced is planar (fltp). This example will output the first channel only. Play the output audio file with the command: ffplay -f f32le -ac 1 -ar 44100 Video_Test_out.aac

查看yuv图片， ffplay -f rawvideo -pix_fmt yuv420p -video_size 1280x720 Video_Test_out.yuv420p.1000.yuv

三、完整代码

#include <stdio.h> #include <stdlib.h> #include <stdbool.h> #include <libavcodec/avcodec.h> #include <libavformat/avformat.h> #include <libavutil/imgutils.h> #include <libavutil/timestamp.h> //av_ts2timestr #include <libavutil/samplefmt.h> #define YUV420P_FILE 1 // 视频流保存成 yuv420p 图片 //#define H264_FILE 1 // 视频流保存成 H264 文件 static int get_format_from_sample_fmt(const char** fmt, enum AVSampleFormat sample_fmt) { int i; struct sample_fmt_entry { enum AVSampleFormat sample_fmt; const char* fmt_be, * fmt_le; } sample_fmt_entries[] = { { AV_SAMPLE_FMT_U8, "u8", "u8" }, { AV_SAMPLE_FMT_S16, "s16be", "s16le" }, { AV_SAMPLE_FMT_S32, "s32be", "s32le" }, { AV_SAMPLE_FMT_FLT, "f32be", "f32le" }, { AV_SAMPLE_FMT_DBL, "f64be", "f64le" }, }; *fmt = NULL; for (i = 0; i < FF_ARRAY_ELEMS(sample_fmt_entries); i++) { struct sample_fmt_entry* entry = &sample_fmt_entries[i]; if (sample_fmt == entry->sample_fmt) { *fmt = AV_NE(entry->fmt_be, entry->fmt_le); return 0; } } fprintf(stderr,"sample format %s is not supported as output format\n", av_get_sample_fmt_name(sample_fmt)); return -1; } // 参考:ffplay.c、demuxing_decoding.c int main(int argc, char* argv[]) { int ret = 0; //printf("%s \n",avcodec_configuration()); // 定义文件名 unsigned char input_filename[] = "video.mp4"; unsigned char out_filename[] = "video_out"; unsigned char video_dst_filename[50]; // = "Video_Test_out.h264"; unsigned char audio_dst_filename[50]; // = "Video_Test_out.aac"; memset(video_dst_filename, '\0', 50); memset(audio_dst_filename, '\0', 50); // 1. 打开文件，分配AVFormatContext 结构体上下文 AVFormatContext* fmt_ctx = NULL; // 定义音视频格式上下文结构体 if (avformat_open_input(&fmt_ctx, input_filename, NULL, NULL) < 0) { printf("Could not open source file %s\n", input_filename); return 0; } // 2. 查找文件对应的流信息 if (avformat_find_stream_info(fmt_ctx, NULL) < 0) { printf("Could not find stream information\n"); return 0; } // 3. 打印流信息 av_dump_format(fmt_ctx, 0, input_filename, 0); // 4. 视频解码器初始化 // 4.1 获取视频对应的stream_index int video_stream_idx = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_VIDEO, -1, -1, NULL, 0); printf("\n#===> Find video_stream_idx = %d\n", video_stream_idx); // 4.2 获取到stream 数据 AVStream* video_st = fmt_ctx->streams[video_stream_idx]; // 4.3 根据 codec_id 查找解码器 AVCodec* video_dec = avcodec_find_decoder(video_st->codecpar->codec_id); // 4.4 初始化解码器上下文信息 AVCodecContext* video_dec_ctx = avcodec_alloc_context3(video_dec); // 4.5 复制 codec 相关参数到解码器上下文中 avcodec_parameters_to_context(video_dec_ctx, video_st->codecpar); printf("\n#===> Find decoder: %s, coded_id:%d long name: %s pix_fmt=%d (%s)\n", video_dec->name, video_dec->id, video_dec->long_name, video_dec_ctx->pix_fmt, av_get_pix_fmt_name(video_dec_ctx->pix_fmt)); // 4.6 初始化并打开解码器 AVDictionary* video_opts = NULL; avcodec_open2(video_dec_ctx, video_dec, &video_opts); // 5. 音频解码器初始化 // 5.1 获取音频对应的stream_index int audio_stream_idx = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_AUDIO, -1, -1, NULL, 0); printf("\n#===> Find audio_stream_idx = %d\n", audio_stream_idx); // 5.2 获取到stream 数据 AVStream* audio_st = fmt_ctx->streams[audio_stream_idx]; // 5.3 根据 codec_id 查找解码器 AVCodec* audio_dec = avcodec_find_decoder(audio_st->codecpar->codec_id); printf("\n#===> Find decoder: %s, coded_id:%d long name: %s\n", audio_dec->name, audio_dec->id, audio_dec->long_name); // 5.4 初始化解码器上下文信息 AVCodecContext* audio_dec_ctx = avcodec_alloc_context3(audio_dec); // 5.5 复制 codec 相关参数到解码器上下文中 avcodec_parameters_to_context(audio_dec_ctx, audio_st->codecpar); // 5.6 初化并打开音频解码器 AVDictionary* audio_opts = NULL; avcodec_open2(audio_dec_ctx, audio_dec, &audio_opts); // 6. 配置视频解复用后要保存的位置 FILE* video_dst_file = NULL, * audio_dst_file = NULL; #ifdef H264_FILE sprintf_s(video_dst_filename, 50, "%s.%s", out_filename, video_dec->name); ret = fopen_s(&video_dst_file, video_dst_filename, "wb"); printf("open file:%s ret:%d\n", video_dst_filename, ret); #endif #ifdef YUV420P_FILE //文件夹名称 char folderName[] = "video"; // 文件夹不存在则创建文件夹 if (_access(folderName, 0) == -1) _mkdir(folderName); sprintf_s(audio_dst_filename, 50, "video/%s.%s", out_filename, audio_dec->name); #else sprintf_s(audio_dst_filename, 50, "%s.%s", out_filename, audio_dec->name); #endif ret = fopen_s(&audio_dst_file, audio_dst_filename, "wb"); printf("open file:%s ret:%d\n", audio_dst_filename, ret); uint8_t* video_dst_data[4] = { NULL }; int video_dst_linesize[4] = { 0 }; // 7. 计算视频数据大小 size_t video_dst_bufsize = av_image_alloc(video_dst_data, video_dst_linesize, video_dec_ctx->width, video_dec_ctx->height, video_dec_ctx->pix_fmt, 1); // 8. 分配并初始化 AVFrame、AVPacket AVFrame* frame = av_frame_alloc(); AVPacket pkt; av_init_packet(&pkt); pkt.data = NULL; pkt.size = 0; int video_frame_count = 0, audio_frame_count = 0; printf("Start read frame\n"); // 9. 循环读取 一帧数据 while (av_read_frame(fmt_ctx, &pkt) >= 0) { // 10. 视频数据解码 if (pkt.stream_index == video_stream_idx) { // 10.1 将 packet 数据 发送给解码器 ret = avcodec_send_packet(video_dec_ctx, &pkt); // 10.2 获取解码后的帧数据 while (ret >= 0) { ret = avcodec_receive_frame(video_dec_ctx, frame); if (ret == AVERROR_EOF || ret == AVERROR(EAGAIN)) { ret = 0; break; } // 10.3 保存帧数据到视频文件中 //printf("#===> video_frame n:%d coded_n:%d ", video_frame_count++, frame->coded_picture_number); av_image_copy(video_dst_data, video_dst_linesize, (const uint8_t**)(frame->data), frame->linesize, video_dec_ctx->pix_fmt, video_dec_ctx->width, video_dec_ctx->height); #ifdef YUV420P_FILE // 10.4 写入文件 sprintf_s(video_dst_filename, 50, "video/%s.%s.%d.yuv", out_filename, av_get_pix_fmt_name(video_dec_ctx->pix_fmt), video_frame_count++); ret = fopen_s(&video_dst_file, video_dst_filename, "wb"); //printf("open file:%s ret:%d\n", video_dst_filename, ret); #endif ret = (int)fwrite(video_dst_data[0], 1, video_dst_bufsize, video_dst_file); //printf("Write Size:%d\n", ret); #ifdef YUV420P_FILE fclose(video_dst_file); #endif } } // 11. 音频数据解码 else if (pkt.stream_index == audio_stream_idx) { // 11.1 将 packet 数据 发送给解码器 ret = avcodec_send_packet(audio_dec_ctx, &pkt); // 11.2 获取解码后的帧数据 while (ret >= 0) { ret = avcodec_receive_frame(audio_dec_ctx, frame); if (ret == AVERROR_EOF || ret == AVERROR(EAGAIN)) { ret = 0; break; } // 11.3 写入文件 //printf("#===> audio_frame n:%d nb_samples:%d pts:%s ", // audio_frame_count++, frame->nb_samples, av_ts2timestr(frame->pts, &audio_dec_ctx->time_base)); ret = (int)fwrite(frame->extended_data[0], 1, frame->nb_samples * av_get_bytes_per_sample(frame->format), audio_dst_file); //printf("Write Size:%d\n", ret); } } av_frame_unref(frame); // 清空AVPacket结构体数据 av_packet_unref(&pkt); if (ret < 0) break; } // 12.发送一个空包,刷新解码器 ret = avcodec_send_packet(video_dec_ctx, NULL); // 12.1 获取解码后的帧数据 while (ret >= 0) { ret = avcodec_receive_frame(video_dec_ctx, frame); if (ret == AVERROR_EOF || ret == AVERROR(EAGAIN)) { printf("break, video ret=%d \n", ret); ret = 0; break; } } ret = avcodec_send_packet(audio_dec_ctx, NULL); // 12.2 获取解码后的帧数据 while (ret >= 0) { ret = avcodec_receive_frame(audio_dec_ctx, frame); if (ret == AVERROR_EOF || ret == AVERROR(EAGAIN)) { printf("break, audio ret=%d \n", ret); ret = 0; break; } } // 13. 解复用完毕 printf("Demuxing succeeded.\n"); printf("Play the output video file with the command:\n" "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s\n", av_get_pix_fmt_name(video_dec_ctx->pix_fmt), video_dec_ctx->width, video_dec_ctx->height, video_dst_filename); #ifdef YUV420P_FILE memset(video_dst_filename, '\0', 50); sprintf_s(video_dst_filename, 50, "%s.%s.%d.yuv", out_filename, av_get_pix_fmt_name(video_dec_ctx->pix_fmt), 0); #endif FILE* bat_dst_file = NULL; char bat_out[100] = ""; memset(bat_out, '\0', 100); sprintf_s(bat_out, 99, "ffplay -f rawvideo -pix_fmt %s -video_size %dx%d %s", av_get_pix_fmt_name(video_dec_ctx->pix_fmt), video_dec_ctx->width, video_dec_ctx->height, video_dst_filename); #ifdef YUV420P_FILE ret = fopen_s(&bat_dst_file, "video/play_video.bat", "wb"); #else ret = fopen_s(&bat_dst_file, "play_video.bat", "wb"); #endif ret = (int)fwrite(bat_out, 1, sizeof(bat_out), bat_dst_file); fclose(bat_dst_file); enum AVSampleFormat sfmt = audio_dec_ctx->sample_fmt; int n_channels = audio_dec_ctx->channels; const char* fmt; if (av_sample_fmt_is_planar(sfmt)) { const char* packed = av_get_sample_fmt_name(sfmt); printf("Warning: the sample format the decoder produced is planar " "(%s). This example will output the first channel only.\n",packed ? packed : "?"); sfmt = av_get_packed_sample_fmt(sfmt); n_channels = 1; } if ((ret = get_format_from_sample_fmt(&fmt, sfmt)) < 0) goto end; printf("Play the output audio file with the command:\n" "ffplay -f %s -ac %d -ar %d %s\n",fmt, n_channels, audio_dec_ctx->sample_rate,audio_dst_filename); #ifdef YUV420P_FILE memset(audio_dst_filename, '\0', 50); sprintf_s(audio_dst_filename, 50, "%s.%s", out_filename, audio_dec->name); #endif memset(bat_out, '\0', 100); sprintf_s(bat_out, 99, "ffplay -f %s -ac %d -ar %d %s",fmt, n_channels, audio_dec_ctx->sample_rate,audio_dst_filename); #ifdef YUV420P_FILE ret = fopen_s(&video_dst_file, "video/play_audio.bat", "wb"); #else ret = fopen_s(&video_dst_file, "play_audio.bat", "wb"); #endif ret = (int)fwrite(bat_out, 1, sizeof(bat_out), bat_dst_file); fclose(video_dst_file); end: avcodec_free_context(&video_dec_ctx); avcodec_free_context(&audio_dec_ctx); avformat_close_input(&fmt_ctx); #ifdef H264_FILE fclose(video_dst_file); #endif fclose(audio_dst_file); av_frame_free(&frame); av_free(video_dst_data[0]); return 0; }