ffmpeg MP3 转换 pcm

#include <stdio.h> #define __STDC_CONSTANT_MACROS extern "C" { #include "libavcodec/avcodec.h" #include "libavformat/avformat.h" #include "libswscale/swscale.h" #include "libswresample/swresample.h" }; //setup_array函数摘自ffmpeg例程 static void setup_array(uint8_t* out[SWR_CH_MAX], AVFrame* in_frame, int format, int samples) { if (av_sample_fmt_is_planar((AVSampleFormat)format)) { int i; int plane_size = av_get_bytes_per_sample((AVSampleFormat)(format & 0xFF)) * samples; format &= 0xFF; //从decoder出来的frame中的data数据不是连续分布的，所以不能这样写：in_frame->data[0]+i*plane_size; for (i = 0; i < in_frame->channels; i++) { out[i] = in_frame->data[i]; } } else { out[0] = in_frame->data[0]; } } int main() { char filepath[] = "bird.mp3"; AVFormatContext *pFormatCtx; int i,videoindex; AVCodecContext *pCodecCtx; AVCodec *pCodec; AVFrame *pFrame, *pFrameYUV; AVPacket *packet; struct SwsContext *img_convert_ctx; int ret, got_audio; FILE *fp_pcm; fp_pcm = fopen("output.pcm", "wb+"); av_register_all(); avformat_network_init(); pFormatCtx = avformat_alloc_context(); if (avformat_open_input(&pFormatCtx, filepath, NULL, NULL) != 0){ printf("Couldn't open input stream.\n"); return -1; } if (avformat_find_stream_info(pFormatCtx, NULL) < 0){ printf("Couldn't find stream information.\n"); return -1; } videoindex = -1; for (i = 0; i < pFormatCtx->nb_streams; i++) if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO){ videoindex = i; break; } if (videoindex == -1){ printf("Didn't find a video stream.\n"); return -1; } pCodecCtx = pFormatCtx->streams[videoindex]->codec; pCodec = avcodec_find_decoder(pCodecCtx->codec_id); if (pCodec == NULL){ printf("Codec not found.\n"); return -1; } if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0){ printf("Could not open codec.\n"); return -1; } pFrame = av_frame_alloc(); //pFrameYUV = av_frame_alloc(); //uint8_t *out_buffer = (uint8_t *)av_malloc(avpicture_get_size(PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height)); //avpicture_fill((AVPicture *)pFrameYUV, out_buffer, PIX_FMT_YUV420P, pCodecCtx->width, pCodecCtx->height); packet = (AVPacket *)av_malloc(sizeof(AVPacket)); //Output Information----------------------------- printf("------------- File Information ------------------\n"); av_dump_format(pFormatCtx, 0, filepath, 0); printf("-------------------------------------------------\n"); while (av_read_frame(pFormatCtx, packet) >= 0){ if (packet->stream_index == videoindex){ //Decode ret = avcodec_decode_audio4(pCodecCtx, pFrame, &got_audio, packet); if (got_audio){ //输入也可能是分平面的，所以要做如下处理 uint8_t* m_ain[SWR_CH_MAX]; setup_array(m_ain, pFrame, pCodecCtx->sample_fmt, pFrame->nb_samples); fwrite(pFrame->data[0], 1, pFrame->linesize[0], fp_pcm); } } } av_free(pFrame); avcodec_close(pCodecCtx); avformat_close_input(&pFormatCtx); return 0; }