Yes, the sample format provided to encoder. Should match the samples you're passing to it.
On Wed, Dec 8, 2021 at 2:44 PM Robert Smith via Libav-user < [email protected]> wrote: > I assume you are talking about encoding? > > On Wednesday, December 8, 2021, 02:26:22 PM EST, Bob Kirnum < > [email protected]> wrote: > > > I assume there is a sample format for 32 bit float, try that instead of > AV_SAMPLE_FMT_S16. > If that does not work you may need to convert samples from 32 bit float to > 16 bit integer. > > On Wed, Dec 8, 2021 at 2:21 PM Robert Smith via Libav-user < > [email protected]> wrote: > > Dumped raw data to binary file, opened it in Audacity, found correct > sampling rate and correctly played audio clip. > I noticed that Audacity shows "32 bit float", as you mentioned in your > previous E-mail that could be the reason why transcoding to uLaw fails. > > Could you clarify what is proper way to resolve the issue? Should I > correct decoding? Thanks > > On Wednesday, December 8, 2021, 12:41:41 PM EST, Bob Kirnum < > [email protected]> wrote: > > > To verify the decoded audio from the MP3 I would simply write the decoded > frames to file (fwrite or similar to a binary file). The resulting file is > a raw PCM file which can be imported with Audacity. You specify the sample > rate, sample format (i.e. 16 bit integer or 32 bit float), etc. When you > get the right settings the audio should play good. > > On Wed, Dec 8, 2021 at 12:01 PM Robert Smith via Libav-user < > [email protected]> wrote: > > Hi, > > Thank you for your response. All my attempts to sort it out failed so far. > Could you clarify how can I verify that I decoded the MP3 to linear PCM > properly? > > I mean as result of decoding I'm getting frames: > avcodec_decode_audio4(pMp3CodecCtx, frame, &gotFrame, &packet) > > So what is next? Write frame to wav file? How? The function > av_interleaved_write_frame > despite its name accept packets not a frames? > > How to check validity of wav container? I usually run "ffprobe -i > Output.wav" to see details. Is there other way? Thanks > > On Monday, December 6, 2021, 11:43:17 AM EST, Bob Kirnum < > [email protected]> wrote: > > > Perhaps the AV_SAMPLE_FMT_S16 is referring to the sample format input to > the G.711 uLaw encoder (input should be 16 bit linear PCM)? Then this > would be correct. Perhaps split the effort and verify that you can decode > the MP3 to linear PCM properly, and encode linear to uLaw properly for > WAV separately? Using the wrong sample rate (not downsampling to 8 kHz) > would not result in noise (what you reported), would just result in the > wrong audio speed. One additional thought, does decoding the MP3 result in > 16 bit integer linear PCM or 32 bit float PCM? If float, that would be a > mismatch and result in noise when encoding to uLaw. > > On Mon, Dec 6, 2021 at 10:40 AM Robert Smith via Libav-user < > [email protected]> wrote: > > If I change > > pCodecCtx->sample_fmt = AV_SAMPLE_FMT_S16; > > to > > pCodecCtx->sample_fmt = AV_SAMPLE_FMT_U8; > > Then I get the following error: > > [pcm_mulaw @ 0x2d33450] Specified sample_fmt is not supported. > > Any idea? Thanks > > On Friday, December 3, 2021, 06:15:54 PM EST, Bob Kirnum < > [email protected]> wrote: > > > G.711 is 8 bits, could be an issue. Also, not sure if you need to > downsample to 8kHz manually or not. > > > On Dec 3, 2021, at 5:36 PM, Robert Smith via Libav-user < > [email protected]> wrote: > > > > pCodecCtx->sample_fmt = AV_SAMPLE_FMT_S16; > > _______________________________________________ > Libav-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/libav-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". > > _______________________________________________ > Libav-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/libav-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". > > _______________________________________________ > Libav-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/libav-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". > _______________________________________________ > Libav-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/libav-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". > > _______________________________________________ > Libav-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/libav-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". > _______________________________________________ > Libav-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/libav-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". > > _______________________________________________ > Libav-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/libav-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". > _______________________________________________ > Libav-user mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/libav-user > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". >
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