ffmpeg extract audio stream from mp4 encode mp3

Read the output to see what codec it is, to set the right filename extension. acodec copy says use the same audio stream that’s already in there. Start with the transcode_aac official anycodings_mp4 example.To extract the audio stream without re-encoding:įfmpeg -i input-video.avi -vn -acodec copy output-audio.aac

You can looking into demuxing.c and anycodings_mp4 muxing.c provided in ffmpeg examples.

You anycodings_mp4 can use av_read_frame(informat, anycodings_mp4 &pkt), anycodings_mp4 avcodec_decode_audio4(in_aud_codec_ctx, anycodings_mp4 pframeT, &got_vid_pkt, &pkt), anycodings_mp4 avcodec_encode_audio2() and anycodings_mp4 av_write_frame().įinally write trailer using anycodings_mp4 av_write_trailer. Now in while loop start reading packet, anycodings_mp4 decode only audio packet encode them and anycodings_mp4 write them in opened output file. Write the output headers using anycodings_mp4 avformat_write_header(outformat, NULL). Now for output file guess the outformat anycodings_mp4 using av_guess_format(NULL, (const anycodings_mp4 char*)outfile, NULL).įind output audio encoder using anycodings_mp4 avcodec_find_encoder(outfmt->audio_codec).Īdd new stream audio stream anycodings_mp4 avformat_new_stream(outformat, anycodings_mp4 out_aud_codec).įill output codec context with desired anycodings_mp4 sample rate, sample fmt, channel etc. anycodings_mp4 Use anycodings_mp4 avcodec_find_decoder(in_aud_strm->codec->codec_id) anycodings_mp4 and avcodec_open2(in_aud_codec_ctx, anycodings_mp4 in_aud_codec, NULL). Once you have input audio stream you can anycodings_mp4 find audio decoder and open the decoder.

Open input file using anycodings_mp4 avformat_open_input( &informat, anycodings_mp4 sourcefile, 0, 0)).įind stream info using anycodings_mp4 avformat_find_stream_info(informat, 0)).įind the audio stream by iterating anycodings_mp4 through streams and comparing codec_type anycodings_mp4 to AVMEDIA_TYPE_AUDIO. Here is the normal flow of anycodings_mp4 steps. You can try using ffmpeg to do it in C anycodings_mp4 or C++.

Ffmpeg extract audio stream from mp4 encode mp3