如何使用FFmpeg抽取音视频的视频数据,代码如下:
// FFmpegTest.cpp : 此文件包含 "main" 函数。程序执行将在此处开始并结束。 // #include "pch.h" #include <iostream> #include "AACFormat.h" #define __STDC_CONSTANT_MACROS #define __STDC_FORMAT_MACROS // For extractVideo #ifndef AV_WB32 # define AV_WB32(p, val) do { uint32_t d = (val); ((uint8_t*)(p))[3] = (d); ((uint8_t*)(p))[2] = (d)>>8; ((uint8_t*)(p))[1] = (d)>>16; ((uint8_t*)(p))[0] = (d)>>24; } while(0) #endif // For extractVideo #ifndef AV_RB16 # define AV_RB16(x) ((((const uint8_t*)(x))[0] << 8) | ((const uint8_t*)(x))[1]) #endif extern "C"{ #include <stdio.h> #include "libavcodec/avcodec.h" #include "libavformat/avformat.h" #include "libavutil/log.h" } // For extractVideo static int alloc_and_copy(AVPacket *out, const uint8_t *sps_pps, uint32_t sps_pps_size, const uint8_t *in, uint32_t in_size) { uint32_t offset = out->size; uint8_t nal_header_size = offset ? 3 : 4; int err; err = av_grow_packet(out, sps_pps_size + in_size + nal_header_size); if (err < 0) return err; if (sps_pps) memcpy(out->data + offset, sps_pps, sps_pps_size); memcpy(out->data + sps_pps_size + nal_header_size + offset, in, in_size); if (!offset) { AV_WB32(out->data + sps_pps_size, 1); } else { (out->data + offset + sps_pps_size)[0] = (out->data + offset + sps_pps_size)[1] = 0; (out->data + offset + sps_pps_size)[2] = 1; } return 0; } // For extractVideo int h264_extradata_to_annexb(const uint8_t *codec_extradata, const int codec_extradata_size, AVPacket *out_extradata, int padding) { uint16_t unit_size; uint64_t total_size = 0; uint8_t *out = NULL, unit_nb, sps_done = 0, sps_seen = 0, pps_seen = 0, sps_offset = 0, pps_offset = 0; const uint8_t *extradata = codec_extradata + 4; static const uint8_t nalu_header[4] = { 0, 0, 0, 1 }; int length_size = (*extradata++ & 0x3) + 1; // retrieve length coded size, 用于指示表示编码数据长度所需字节数 sps_offset = pps_offset = -1; /* retrieve sps and pps unit(s) */ unit_nb = *extradata++ & 0x1f; /* number of sps unit(s) */ if (!unit_nb) { goto pps; } else { sps_offset = 0; sps_seen = 1; } while (unit_nb--) { int err; unit_size = AV_RB16(extradata); total_size += unit_size + 4; if (total_size > INT_MAX - padding) { av_log(NULL, AV_LOG_ERROR, "Too big extradata size, corrupted stream or invalid MP4/AVCC bitstream "); av_free(out); return AVERROR(EINVAL); } if (extradata + 2 + unit_size > codec_extradata + codec_extradata_size) { av_log(NULL, AV_LOG_ERROR, "Packet header is not contained in global extradata, " "corrupted stream or invalid MP4/AVCC bitstream "); av_free(out); return AVERROR(EINVAL); } if ((err = av_reallocp(&out, total_size + padding)) < 0) return err; memcpy(out + total_size - unit_size - 4, nalu_header, 4); memcpy(out + total_size - unit_size, extradata + 2, unit_size); extradata += 2 + unit_size; pps: if (!unit_nb && !sps_done++) { unit_nb = *extradata++; /* number of pps unit(s) */ if (unit_nb) { pps_offset = total_size; pps_seen = 1; } } } if (out) memset(out + total_size, 0, padding); if (!sps_seen) av_log(NULL, AV_LOG_WARNING, "Warning: SPS NALU missing or invalid. " "The resulting stream may not play. "); if (!pps_seen) av_log(NULL, AV_LOG_WARNING, "Warning: PPS NALU missing or invalid. " "The resulting stream may not play. "); out_extradata->data = out; out_extradata->size = total_size; return length_size; } // For extractVideo int h264_mp4toannexb(AVFormatContext *fmt_ctx, AVPacket *in, FILE *dst_fd) { AVPacket *out = NULL; AVPacket spspps_pkt; int len; uint8_t unit_type; int32_t nal_size; uint32_t cumul_size = 0; const uint8_t *buf; const uint8_t *buf_end; int buf_size; int ret = 0, i; out = av_packet_alloc(); buf = in->data; buf_size = in->size; buf_end = in->data + in->size; do { ret = AVERROR(EINVAL); if (buf + 4 /*s->length_size*/ > buf_end) goto fail; for (nal_size = 0, i = 0; i < 4/*s->length_size*/; i++) nal_size = (nal_size << 8) | buf[i]; buf += 4; /*s->length_size;*/ unit_type = *buf & 0x1f; if (nal_size > buf_end - buf || nal_size < 0) goto fail; /* if (unit_type == 7) s->idr_sps_seen = s->new_idr = 1; else if (unit_type == 8) { s->idr_pps_seen = s->new_idr = 1; */ /* if SPS has not been seen yet, prepend the AVCC one to PPS */ /* if (!s->idr_sps_seen) { if (s->sps_offset == -1) av_log(ctx, AV_LOG_WARNING, "SPS not present in the stream, nor in AVCC, stream may be unreadable "); else { if ((ret = alloc_and_copy(out, ctx->par_out->extradata + s->sps_offset, s->pps_offset != -1 ? s->pps_offset : ctx->par_out->extradata_size - s->sps_offset, buf, nal_size)) < 0) goto fail; s->idr_sps_seen = 1; goto next_nal; } } } */ /* if this is a new IDR picture following an IDR picture, reset the idr flag. * Just check first_mb_in_slice to be 0 as this is the simplest solution. * This could be checking idr_pic_id instead, but would complexify the parsing. */ /* if (!s->new_idr && unit_type == 5 && (buf[1] & 0x80)) s->new_idr = 1; */ /* prepend only to the first type 5 NAL unit of an IDR picture, if no sps/pps are already present */ if (/*s->new_idr && */unit_type == 5 /*&& !s->idr_sps_seen && !s->idr_pps_seen*/) { h264_extradata_to_annexb(fmt_ctx->streams[in->stream_index]->codec->extradata, fmt_ctx->streams[in->stream_index]->codec->extradata_size, &spspps_pkt, AV_INPUT_BUFFER_PADDING_SIZE); if ((ret = alloc_and_copy(out, spspps_pkt.data, spspps_pkt.size, buf, nal_size)) < 0) goto fail; /*s->new_idr = 0;*/ /* if only SPS has been seen, also insert PPS */ } /*else if (s->new_idr && unit_type == 5 && s->idr_sps_seen && !s->idr_pps_seen) { if (s->pps_offset == -1) { av_log(ctx, AV_LOG_WARNING, "PPS not present in the stream, nor in AVCC, stream may be unreadable "); if ((ret = alloc_and_copy(out, NULL, 0, buf, nal_size)) < 0) goto fail; } else if ((ret = alloc_and_copy(out, ctx->par_out->extradata + s->pps_offset, ctx->par_out->extradata_size - s->pps_offset, buf, nal_size)) < 0) goto fail; }*/ else { if ((ret = alloc_and_copy(out, NULL, 0, buf, nal_size)) < 0) goto fail; /* if (!s->new_idr && unit_type == 1) { s->new_idr = 1; s->idr_sps_seen = 0; s->idr_pps_seen = 0; } */ } len = fwrite(out->data, 1, out->size, dst_fd); if (len != out->size) { av_log(NULL, AV_LOG_DEBUG, "warning, length of writed data isn't equal pkt.size(%d, %d) ", len, out->size); } fflush(dst_fd); next_nal: buf += nal_size; cumul_size += nal_size + 4;//s->length_size; } while (cumul_size < buf_size); /* ret = av_packet_copy_props(out, in); if (ret < 0) goto fail; */ fail: av_packet_free(&out); return ret; } // 使用FFmpeg从视频中抽取视频 void extractVideo() { // Start Code 特征码 // PSP PPS(从codec->extradata即在数据空间中存放) // 设置日志输出等级 av_log_set_level(AV_LOG_INFO); AVFormatContext *fmt_ctx = NULL; AVPacket pkt; // 注册所有的格式和编解码器 av_register_all(); int ret; int len; int video_index = -1; // 打开输入文件 ret = avformat_open_input(&fmt_ctx, "111.mp4", NULL, NULL); // 检查打开输入文件是否成功 if (ret < 0) { printf("cant open file,error message = %s", av_err2str(ret)); return; } // 打开输出文件 FILE* dst_fd = fopen("111.H264", "wb"); // w 写入 b 二进制文件 // 检查输出文件打开是否成功,如果失败,就输出日志,并关闭输出文件的引用 if (!dst_fd) { av_log(NULL, AV_LOG_ERROR, "Can't Open Out File! "); avformat_close_input(&fmt_ctx); } av_init_packet(&pkt); pkt.data = NULL; pkt.size = 0; for (int i = 0; i < fmt_ctx->nb_streams; i++) { if (fmt_ctx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) { video_index = i; break; } } printf("Video Stream Index = %d", video_index); // 检查发现视频流的结果 if (video_index < 0) { av_log(NULL, AV_LOG_ERROR, "Can't find Best Video Stream! "); //printf("Reason = %s", av_err2str(ret)); // 关闭输出文件和输出文件的引用 avformat_close_input(&fmt_ctx); fclose(dst_fd); return; } while (av_read_frame(fmt_ctx, &pkt) >= 0) { if (pkt.stream_index == video_index) { h264_mp4toannexb(fmt_ctx, &pkt, dst_fd); } // 将引用基数减一 av_packet_unref(&pkt); } // 关闭文件(输入/输出) avformat_close_input(&fmt_ctx); if (dst_fd) { fclose(dst_fd); } } int main(int argc, char* argv[]) { /**使用FFmpeg从视频中抽取视频 **/ extractVideo(); return 0; }