davidgrisham
commented
11 months ago I've now gotten aplay+ to output very clicky/noisy audio, and I can sort of hear the actual song underneath. I updated the uaac_extract_aac function to:
uint8_t *uaac_extract_aac(int fd, int *len, int *samplerate, int *channels)
{
_ATOM ftyp = uaac_findMp4Atom("ftyp", 0, 0, fd);
if (!ftyp.size) return 0; // no mp4/m4a file
_ATOM free = uaac_findMp4Atom("free", ftyp.pos + ftyp.size, 1, fd);
if (!free.size) return 0; // no mp4/m4a file
_ATOM mdat = uaac_findMp4Atom("mdat", free.pos + free.size, 1, fd);
printf("mdat.size: %d\n", mdat.size);
*len = mdat.size;
uint8_t *data = (uint8_t*)malloc(mdat.size);
if (!data) return 0; // memory error!
ssize_t bytes_read = read(fd, data, mdat.size);
printf("bytes_read: %zd\n", bytes_read);
_ATOM moov = uaac_findMp4Atom("moov", mdat.pos + mdat.size, 0, fd);
_ATOM trak = uaac_findMp4Atom("trak", moov.pos + 8, 1, fd);
_ATOM mdia = uaac_findMp4Atom("mdia", trak.pos + 8, 1, fd);
_ATOM mdhd = uaac_findMp4Atom("mdhd", mdia.pos + 8, 1, fd);
_ATOM hdlr = uaac_findMp4Atom("hdlr", mdhd.pos + mdhd.size, 1, fd);
_ATOM minf = uaac_findMp4Atom("minf", hdlr.pos + hdlr.size, 1, fd);
_ATOM stbl = uaac_findMp4Atom("stbl", minf.pos + 8, 1, fd);
_ATOM stsd = uaac_findMp4Atom("stsd", stbl.pos + 8, 1, fd);
if (!stsd.size) return 0; // something is not ok
*channels = uaac_read16(stsd.pos + 8 + 0x20, fd);
*samplerate = uaac_read32(stsd.pos + 8 + 0x26, fd);
printf("channels: %d\n", *channels);
printf("samplerate: %d\n", *samplerate);
return data;
}And after recompiling + running aplay+ the terminal output is:
$ ./aplay+ -d 'hw:2,0' files/
/home/grish/scratch/aplay-/files/output.m4a
mdat.size: 7727795
bytes_read: 7727795
channels: 2
samplerate: 48000
48000Hz 2chIn case it's helpful, here's the data ffmpeg extracts from the same audio file:
$ ffprobe -i output.m4a
ffprobe version n6.0 Copyright (c) 2007-2023 the FFmpeg developers
built with gcc 13.2.1 (GCC) 20230801
configuration: --prefix=/usr --disable-debug --disable-static --disable-stripping --enable-amf --enable-avisynth --enable-cuda-llvm --enable-lto --enable-fontconfig --enable-gmp --enable-gpl --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libdav1d --enable-libdrm --enable-libfreetype --enable-libfribidi --enable-libgsm --enable-libiec61883 --enable-libjack --enable-libjxl --enable-libmodplug --enable-libmp3lame --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librav1e --enable-librsvg --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libv4l2 --enable-libvidstab --enable-libvmaf --enable-libvorbis --enable-libvpl --enable-libvpx --enable-libwebp --enable-libx264 --enable-libx265 --enable-libxcb --enable-libxml2 --enable-libxvid --enable-libzimg --enable-nvdec --enable-nvenc --enable-opencl --enable-opengl --enable-openssl --enable-shared --enable-vaapi --enable-version3 --enable-vulkan --enable-libfdk_aac --enable-nonfree --disable-htmlpages
libavutil 58. 2.100 / 58. 2.100
libavcodec 60. 3.100 / 60. 3.100
libavformat 60. 3.100 / 60. 3.100
libavdevice 60. 1.100 / 60. 1.100
libavfilter 9. 3.100 / 9. 3.100
libswscale 7. 1.100 / 7. 1.100
libswresample 4. 10.100 / 4. 10.100
libpostproc 57. 1.100 / 57. 1.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'output.m4a':
Metadata:
major_brand : M4A
minor_version : 512
compatible_brands: M4A isomiso2
title : Irresistible
artist : Deafheaven
composer : George Clarke/Kerry McCoy
album : Sunbather (10th Anniversary Remix / Remaster)
genre : Black Metal
track : 2
disc : 0
date : 2023
compilation : 0
encoder : Lavf60.3.100
ORIGINAL YEAR : 0000
lyrics :
sort_album_artist:
sort_artist :
sort_composer :
grouping :
comment : ~ N ~
album_artist : Deafheaven
Duration: 00:03:13.15, start: 0.000000, bitrate: 321 kb/s
Stream #0:0[0x1](und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 320 kb/s (default)
Metadata:
handler_name : SoundHandler
vendor_id : [0][0][0][0]
Hi!
I'm working on integrating
uaac.has an AAC decoder forminiaudio, but I'm having issues gettinguaacto decode my AAC files in the first place. I'm using ffmpeg andlibfdk_aac(Fraunhofer FDK AAC) to encode my files. I've tested with youraplay+program and am getting the same issue.I have two files in the following test:
output.m4awas encoded with the defaultffmpeg/libfdk_aacsettingsoutput-moov.m4awas encoded the same way, but I passed the-movflags +faststartoptions so that themoovatom would be at the start of the file (sinceuaacwasn't able to find it)I've been playing around with the
uaac_extract_aacfunction, but am not well-versed in decoding audio files. Curious if you have any ideas here, or at least a sense of how much work it would be to get this working. I have a rather large audio library that's encoded in the same way, so I'm hoping to get this working without modifying the audio files.