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I have an audio record that is precious to me, was made years ago, and I got it via an mms type of message on my old GSM phone.

According to ffprobe.exe -show_entries format:stream -count_frames -count_packets -i mms-1.amr > input.txt, the audio has the following specs:

    [STREAM]
    codec_name=amr_nb
    codec_long_name=AMR-NB (Adaptive Multi-Rate NarrowBand)
    codec_time_base=1/8000
    codec_tag_string=samr
    sample_rate=8000
    channels=1
    channel_layout=mono
    bits_per_sample=0
    duration_ts=275840
    duration=34.480000
    bit_rate=6000
    nb_read_frames=1724
    nb_read_packets=1724
    [/STREAM]
    [FORMAT]
    filename=mms-1.amr
    nb_streams=1
    format_long_name=3GPP AMR
    bit_rate=6401
    probe_score=100
    [/FORMAT]

So, I tried several times with ffmpeg but the only workable approach I found was a two leg conversion, extracting the raw audio first:

1)ffmpeg -i mms-1.amr -f s16le -c:a pcm_s16le output.raw

2)ffmpeg -f s16le -ar 8000 -ac 1 -i output.raw mms-1.wav

Interestingly, the original file size is 27KB, the wave file is 539KB!

Two questions:

  1. Is this the only way to convert an .amr type of audio file into any format to be easily recognised by Windows system? What about a single line of code to convert straight into wav format?

  2. Is there /are there/ any good audio filters within ffmpeg to accentuate a voice in the record. The answer to an old question here mentions "equalizing as a proper technique to filter noise out and improve voice recognition..." but I failed so far to find a good explanation of how it works. Any other filters?

USIKPA
  • 61

0 Answers0