mstorsjo
commented
9 years ago First off, the libavcodec decoder probably is a better choice for most cases. The wrapper for using fdk-aac for decoding via libavcodec was added before libavcodec itself supported the newer profiles like AAC-LD and AAC-ELD. There shouldn't be much difference - except that the fdk decoder wrapper (that is, the libavcodec integration of it, not the fdk-aac decoder itself) is less tested.
As for the missing profile info, this is just because the fdk-aac decoder wrapper doesn't expose the profile info at all.
The issue seems to be that the fdk-aac decoder first returns a few mono frames before it realizes that this should decode into stereo, and the libavcodec fdk-aac decoder wrapper doesn't support streams that change format right now.
You could try something like this:
diff --git a/libavcodec/libfdk-aacdec.c b/libavcodec/libfdk-aacdec.c
index f789b75..ab7bdfa 100644
--- a/libavcodec/libfdk-aacdec.c
+++ b/libavcodec/libfdk-aacdec.c
@@ -328,7 +328,7 @@ static int fdk_aac_decode_frame(AVCodecContext *avctx, void *data,
return AVERROR_INVALIDDATA;
}
- if (s->initialized) {
+ if (s->initialized && 0) {
frame->nb_samples = avctx->frame_size;
if ((ret = ff_get_buffer(avctx, frame, 0)) < 0) {
av_log(avctx, AV_LOG_ERROR, "ff_get_buffer() failed\n");
@@ -366,7 +366,7 @@ static int fdk_aac_decode_frame(AVCodecContext *avctx, void *data,
goto end;
}
- if (!s->initialized) {
+ if (!s->initialized || 1) {
if ((ret = get_stream_info(avctx)) < 0)
goto end;
s->initialized = 1;
@@ -385,7 +385,7 @@ static int fdk_aac_decode_frame(AVCodecContext *avctx, void *data,
avctx->channels * avctx->frame_size *
av_get_bytes_per_sample(avctx->sample_fmt));
- if (!s->anc_buffer)
+ if (!s->anc_buffer && 0)
av_freep(&s->decoder_buffer);
}This is a crude hack to make it support changing stream format a bit better, at the expense of more unnecessary copying of data.
Vangelis66
gmittal42
Hello Martin :-)
Many thanks for your hard work! I recently was able to compile on my Vista x86 laptop a non-free FFmpeg binary, with: --enable-gpl --enable-nonfree --enable-libfdk-aac using jb's build script @ https://github.com/jb-alvarado/media-autobuild_suite
I was conducting some experiments lately using libfdk-aac as an AAC decoder, overriding FFmpeg's native aac decoder, to investigate the difference, if any...
As input files I used some BBC Radio 1 live streams. While the following commands worked as expected:
ffmpeg -c:a libfdk_aac -re -i "http://bbcmedia.ic.llnwd.net/stream/bbcmedia_intl_lc_radio1_q" -t 60 -c:a libmp3lame -b:a 128k -ar 44100 -ac 2 "BBC Radio 1 Live (56aaclc-128mp3).mp3"
(stream is encoded with AAC LC profile) and
ffmpeg -c:a libfdk_aac -re -i "http://as-hls-ww-live.bbcfmt.vo.llnwd.net/pool_7/live/bbc_radio_one/bbc_radio_one.isml/bbc_radio_one-audio=48000.m3u8" -t 60 -c:a libmp3lame -b:a 112k -ar 44100 -ac 2 "BBC Radio 1 Live (48heaac-112mp3).mp3"
(stream is encoded with HE-AACv1 profile), the next command, in which the live stream is encoded with the HE-AACv2 profile, causes FFmpeg to crash:
ffmpeg -c:a libfdk_aac -re -i "http://bbcmedia.ic.llnwd.net/stream/bbcmedia_intl_he_radio1_q" -t 60 -c:a libmp3lame -b:a 112k -ar 44100 -ac 2 "BBC Radio 1 Live (48heaac2-112mp3).mp3"
Sometimes I get an "Error number -12 occurred" :
Stream mapping: Stream #0:0 -> #0:0 (aac (libfdk_aac) -> mp3 (libmp3lame)) Press [q] to stop, [?] for help Error while decoding stream #0:0: Error number -12 occurred Last message repeated 1 times
but usually ffmpeg crashes right after I hit enter; adding -v 48 as an input option does not reveal anything useful, either. Sadly, I am not very savvy to debug this myself; I know libfdk_aac can encode with "-profile:a aac_he_v2", so I regarded it a given that it could decode, too (which is probably the case). However, this fails in my build and system... It looks as though libfdk_aac picks up the stream as AAC (LC) with SR=22050 Hz and in mono (Stream #0:0, 50, 1/28224000: Audio: aac, 22050 Hz, mono, s16, 46 kb/s), whereas using the native decoder it is correctly identified as HE-AACv2:
Stream #0:0, 50, 1/28224000: Audio: aac (HE-AACv2), 44100 Hz, stereo, fltp, 44 kb/s
Any insight will be greatly appreciated! Keep up the pristine job!
Kind regards, Vangelis.