<div dir="ltr">Perhaps the <span style="color:rgb(38,40,42);font-family:"Helvetica Neue",Helvetica,Arial,sans-serif;font-size:16px">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 </span><span style="color:rgb(38,40,42);font-family:"Helvetica Neue",Helvetica,Arial,sans-serif;font-size:16px">properly<span class="gmail-Apple-converted-space"> </span></span><span style="color:rgb(38,40,42);font-family:"Helvetica Neue",Helvetica,Arial,sans-serif;font-size:16px">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.</span></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Mon, Dec 6, 2021 at 10:40 AM Robert Smith via Libav-user <<a href="mailto:libav-user@ffmpeg.org">libav-user@ffmpeg.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-style:solid;border-left-color:rgb(204,204,204);padding-left:1ex"><div><div style="font-family:"Helvetica Neue",Helvetica,Arial,sans-serif;font-size:16px"><div></div>
<div dir="ltr">If I change<br><br><span><span style="color:rgb(38,40,42);font-family:"Helvetica Neue",Helvetica,Arial,sans-serif">pCodecCtx->sample_fmt = AV_SAMPLE_FMT_S16;<br></span></span><br>to<br><br><span><span style="color:rgb(38,40,42);font-family:"Helvetica Neue",Helvetica,Arial,sans-serif">pCodecCtx->sample_fmt = AV_SAMPLE_FMT_U8;<br></span></span><br>Then I get the following error:<br><br><span>[pcm_mulaw @ 0x2d33450] Specified sample_fmt is not supported.<br></span><br>Any idea? Thanks</div><div><br></div>
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On Friday, December 3, 2021, 06:15:54 PM EST, Bob Kirnum <<a href="mailto:bkirnum@gmail.com" target="_blank">bkirnum@gmail.com</a>> wrote:
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<div><div dir="ltr">G.711 is 8 bits, could be an issue. Also, not sure if you need to downsample to 8kHz manually or not. <br clear="none"><div id="gmail-m_20558058468712755ydp31fd7335yqtfd51216"><br clear="none">> On Dec 3, 2021, at 5:36 PM, Robert Smith via Libav-user <<a shape="rect" href="mailto:libav-user@ffmpeg.org" rel="nofollow" target="_blank">libav-user@ffmpeg.org</a>> wrote:<br clear="none">> <br clear="none">> pCodecCtx->sample_fmt = AV_SAMPLE_FMT_S16;</div><br clear="none">_______________________________________________<br clear="none">Libav-user mailing list<br clear="none"><a shape="rect" href="mailto:Libav-user@ffmpeg.org" rel="nofollow" target="_blank">Libav-user@ffmpeg.org</a><br clear="none"><a shape="rect" href="https://ffmpeg.org/mailman/listinfo/libav-user" rel="nofollow" target="_blank">https://ffmpeg.org/mailman/listinfo/libav-user</a><br clear="none"><br clear="none">To unsubscribe, visit link above, or email<br clear="none"><a shape="rect" href="mailto:libav-user-request@ffmpeg.org" rel="nofollow" target="_blank">libav-user-request@ffmpeg.org</a> with subject "unsubscribe".<div id="gmail-m_20558058468712755ydp31fd7335yqtfd92186"><br clear="none"></div></div></div>
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