<html><head><meta http-equiv="Content-Type" content="text/html charset=utf-8"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space;" class="">Hi guys,<br class=""><div class=""><br class=""></div><div class="">I just received a movie file with AAC audio which doesn't play correctly in my player using the ffmpeg libraries.</div><div class="">It sounded “robotic” and the audio ran out of sync rather quickly.</div><div class=""><br class=""></div><div class="">Ffprobe output:</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">ffprobe version 3.3.1 Copyright (c) 2007-2017 the FFmpeg developers</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> built with llvm-gcc 4.2.1 (LLVM build 2336.11.00)</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-libgsm --enable-libvidstab --enable-libx265 --disable-doc --arch=x86_64 --enable-runtime-cpudetect</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> libavutil 55. 58.100 / 55. 58.100</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> libavcodec 57. 89.100 / 57. 89.100</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> libavformat 57. 71.100 / 57. 71.100</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> libavdevice 57. 6.100 / 57. 6.100</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> libavfilter 6. 82.100 / 6. 82.100</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> libswscale 4. 6.100 / 4. 6.100</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> libswresample 2. 7.100 / 2. 7.100</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> libpostproc 54. 5.100 / 54. 5.100</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class="">Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '/Users/flo/Downloads/wetransfer-6ec47f/IQT Capture 170911 Unity Round1.mov':</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> Metadata:</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> major_brand : qt </span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> minor_version : 512</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> compatible_brands: qt </span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> encoder : Lavf57.66.102</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> Duration: 00:07:58.81, start: 0.000000, bitrate: 2672 kb/s</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720, 2499 kb/s, 29.97 fps, 29.97 tbr, 30k tbn, 59.94 tbc (default)</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> Metadata:</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> handler_name : DataHandler</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 162 kb/s (default)</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> Metadata:</span></div><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo; background-color: rgb(255, 255, 255);" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""> handler_name : DataHandler</span></div></div><div class=""><br class=""></div><div class="">By examining the file I found out that the packet durations of the AAC stream were not 1024 as they are with all the other files I have but rather either 1000 or 1100.</div><div class="">While this by itself would not be a problem, it’s very confusing that the AAC decoder outputs AVFrames with a duration of 1024.</div><div class=""><br class=""></div><div class="">So now I’m a bit stuck as I really don’t know what to do.</div><div class="">If the packets were all 1000 I would try discarding the last 24 samples of each AVFrame but as the frame apparently only holds 1024 samples although the packet says it contains 1100 samples, I’m stuck.</div><div class="">I tried sending a NULL packet in the case of longer packets hoping to get the remains 76 samples out of the decoder but I got this error message:</div><div class=""><br class=""></div><div class=""><div style="margin: 0px; font-size: 11px; line-height: normal; font-family: Menlo;" class=""><span style="font-variant-ligatures: no-common-ligatures" class=""><b class="">[aac @ 0x10539da00] Got unexpected packet size after a partial decode</b></span></div></div><div class=""><br class=""></div><div class="">The file plays fine in both QuickTime and VLC so there must be a correct way of handling these kind of files..</div><div class=""><br class=""></div><div class="">I’d be very grateful for any insight anyone of you might have!</div><div class=""><br class=""></div><div class="">Thanks and best,</div><div class=""><br class=""></div><div class="">Flo</div></body></html>