#3175: audio (aac) silently on streamcopy from mpegts to flv
-------------------------------------+-------------------------------------
Reporter: iluvatar | Type: defect
Status: new | Priority: normal
Component: avformat | Version: git-
Keywords: aac | master
streamcopy flv | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
-------------------------------------+-------------------------------------
If you do streamcopy from mpegts to flv with audiocodec aac audio in
output is silently.
Reproduced with internal aac encoder, faac and libfdk_aac.
The problem occurs, because AudioSpecificConfig (ASC) is not written on
streamcopy. Bitstream filter aac_adtstoasc_bsf.c writes ASC correctly
(line 94-99) but too late (after flv header).
If you write ASC in flvenc.c manually, encoded file is written correctly:
{{{
--- a/libavformat/flvenc.c
+++ b/libavformat/flvenc.c
@@ -397,7 +397,8 @@ static int flv_write_header(AVFormatContext *s)
if (enc->codec_id == AV_CODEC_ID_AAC) {
avio_w8(pb, get_audio_flags(s, enc));
avio_w8(pb, 0); // AAC sequence header
- avio_write(pb, enc->extradata, enc->extradata_size);
+ avio_wb16(pb, 5000); // ^= 0x1388; AAC LC, 22050 Hz, 1
channel
+ //avio_write(pb, enc->extradata, enc->extradata_size);
} else {
avio_w8(pb, enc->codec_tag | FLV_FRAME_KEY); // flags
avio_w8(pb, 0); // AVC sequence header
}}}
More information about ASC:
http://wiki.multimedia.cx/index.php?title=MPEG-
4_Audio#Audio_Specific_Config
I don't know if you can call bitstream filter before writing flv header.
How to reproduce:
{{{
% ffmpeg -re -i /tmp/input.ts -c:v copy -c:a libfaac -b:a 32k -ar 22050
-ac 1 -f mpegts udp://localhost:1234
ffmpeg version N-58470-g3c846fd Copyright (c) 2000-2013 the FFmpeg
developers
built on Nov 26 2013 14:56:57 with gcc 4.4.5 (Debian 4.4.5-8)
configuration: --enable-nonfree --enable-libfaac --enable-libx264
--enable-gpl --enable-libzmq --enable-libfreetype --enable-ffplay
--enable-librtmp --enable-libfdk-aac --enable-libmp3lame --enable-libvpx
libavutil 52. 55.100 / 52. 55.100
libavcodec 55. 44.100 / 55. 44.100
libavformat 55. 21.102 / 55. 21.102
libavdevice 55. 5.100 / 55. 5.100
libavfilter 3. 91.100 / 3. 91.100
libswscale 2. 5.101 / 2. 5.101
libswresample 0. 17.104 / 0. 17.104
libpostproc 52. 3.100 / 52. 3.100
Input #0, mpegts, from '/tmp/input.ts':
Duration: 00:01:00.00, start: 1.378667, bitrate: 2319 kb/s
Program 1
Metadata:
service_name : Service01
service_provider: FFmpeg
Stream #0:0[0x100]: Video: h264 (Main) ([27][0][0][0] / 0x001B),
yuv420p, 1280x720 [SAR 1:1 DAR 16:9], 50 fps, 50 tbr, 90k tbn, 100 tbc
Stream #0:1[0x101](deu): Audio: aac ([15][0][0][0] / 0x000F), 48000
Hz, stereo, fltp, 121 kb/s
Output #0, mpegts, to 'udp://localhost:1234':
Metadata:
encoder : Lavf55.21.102
Stream #0:0: Video: h264 ([27][0][0][0] / 0x001B), yuv420p, 1280x720
[SAR 1:1 DAR 16:9], q=2-31, 50 fps, 90k tbn, 50 tbc
Stream #0:1(deu): Audio: aac (libfaac), 22050 Hz, mono, s16, 32 kb/s
Stream mapping:
Stream #0:0 -> #0:0 (copy)
Stream #0:1 -> #0:1 (aac -> libfaac)
Press [q] to stop, [?] for help
% ffmpeg -i udp://localhost:1234 -c copy -bsf:a aac_adtstoasc -f flv
output.flv
}}}
My intention is to stream one mpegts (with one h264 and multiple languages
-> aac) to a local udp port and then steam each language in extra
processes to different flash servers.
--
Ticket URL: <https://trac.ffmpeg.org/ticket/3175>
FFmpeg <http://ffmpeg.org>
FFmpeg issue tracker
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