#7550: Audible artifacts when converting from WAV to AAC -------------------------------------+------------------------------------- Reporter: sleroux | Type: defect Status: new | Priority: normal Component: | Version: git- undetermined | master Keywords: | Blocked By: Blocking: | Reproduced by developer: 0 Analyzed by developer: 0 | -------------------------------------+------------------------------------- While converting a WAV file to AAC I noticed audible audio artifacts. Especially, the artifacts seem to appear on only one channel even in dual- mono.
The issue has improved in the latest build compared to ffmpeg 3.2.12-1~deb9u1 used on our Debian 9.4 production host but is still clearly audible. A particularly audible artifact is present between 00:05:30.930 and 00:05:30.940 is the attached example file. I copied the audio files in extenso since the artifact seems to vanish when I trim the input file. Attached: * EP26-wav-to-aac-artifacts-orig.wav : the original uncompressed audio file * EP26-wav-to-aac-artifacts-ffmpeg-debian-stable.mp4 : the audio transcoded as AAC by ffmpeg 3.2.12-1~deb9u1 on our Debian 9.4 production host * EP26-wav-to-aac-artifacts-ffmpeg-static-latest.mp4 : the audio transcoded as AAC by the latest ffmpeg static build * Audacity screen capture pinpointing an artifact (first stereo pair is original WAV, second stereo pair is output produced by ffmpeg on Debian 9.4, third stereo pair in output produced by the lattest ffmpeg static build) How to reproduce: {{{ $ /tmp/ffmpeg-git-20181115-amd64-static/ffmpeg -i EP26-wav-to-aac- artifacts-orig.wav -c:a aac EP26-wav-to-aac-artifacts-ffmpeg-debian- stable.mp4 ffmpeg version N-47455-g1096614c42-static https://johnvansickle.com/ffmpeg/ Copyright (c) 2000-2018 the FFmpeg developers built with gcc 6.3.0 (Debian 6.3.0-18+deb9u1) 20170516 configuration: --enable-gpl --enable-version3 --enable-static --disable- debug --disable-ffplay --disable-indev=sndio --disable-outdev=sndio --cc=gcc-6 --enable-fontconfig --enable-frei0r --enable-gnutls --enable- gray --enable-libaom --enable-libfribidi --enable-libass --enable-libvmaf --enable-libfreetype --enable-libmp3lame --enable-libopencore-amrnb --enable-libopencore-amrwb --enable-libopenjpeg --enable-librubberband --enable-libsoxr --enable-libspeex --enable-libvorbis --enable-libopus --enable-libtheora --enable-libvidstab --enable-libvo-amrwbenc --enable- libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzimg libavutil 56. 23.101 / 56. 23.101 libavcodec 58. 39.100 / 58. 39.100 libavformat 58. 22.100 / 58. 22.100 libavdevice 58. 6.100 / 58. 6.100 libavfilter 7. 43.100 / 7. 43.100 libswscale 5. 4.100 / 5. 4.100 libswresample 3. 4.100 / 3. 4.100 libpostproc 55. 4.100 / 55. 4.100 Guessed Channel Layout for Input Stream #0.0 : stereo Input #0, wav, from 'EP26-wav-to-aac-artifacts-orig.wav': Duration: 00:07:46.24, bitrate: 1536 kb/s Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, stereo, s16, 1536 kb/s Stream mapping: Stream #0:0 -> #0:0 (pcm_s16le (native) -> aac (native)) Press [q] to stop, [?] for help Output #0, mp4, to 'EP26-wav-to-aac-artifacts-ffmpeg-debian-stable-2.mp4': Metadata: encoder : Lavf58.22.100 Stream #0:0: Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s Metadata: encoder : Lavc58.39.100 aac size= 6513kB time=00:07:46.24 bitrate= 114.4kbits/s speed=36.3x video:0kB audio:6427kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 1.342028% [aac @ 0x55cedc0] Qavg: 15720.868 }}} -- Ticket URL: <https://trac.ffmpeg.org/ticket/7550> FFmpeg <https://ffmpeg.org> FFmpeg issue tracker _______________________________________________ FFmpeg-trac mailing list FFmpeg-trac@avcodec.org http://ffmpeg.org/mailman/listinfo/ffmpeg-trac