id	summary	reporter	owner	description	type	status	priority	component	version	resolution	keywords	cc	blockedby	blocking	reproduced	analyzed
356	-profile aac_low option sets also the profile for the video codec	tfoucu		"ex:
./ffmpeg -i trailer_720p.20.flv -b 56000 -vf scale=176:144 -level 8 -vcodec mpeg4 -ab 24000 -ar 22050 -ac 1 -profile aac_low -acodec libfaac -f mp4 -y /tmp/test.mp4

will generate a mp4 file with the video codec profile/level to be 24

output from mp4info:
Track   Type    Info
1       video   '''MPEG-4 Unknown Profile(24)''', 211.085 secs, 63 kbps, 176x144 @ 23.976123 fps
2       audio   MPEG-4 AAC LC, 211.162 secs, 24 kbps, 22050 Hz


if you remove the profile option from the command line, output of mp4info
Track   Type    Info
1       video   MPEG-4 Simple @ L0, 211.085 secs, 63 kbps, 176x144 @ 23.976123 fps
2       audio   MPEG-4 AAC LC, 211.162 secs, 24 kbps, 22050 Hz


So, it seems that -profile aac_low does set the profile of the video encoder context to be 1 as well as the audio encoder context. 


The exact output of the command line with -profile aac_low
./ffmpeg -i trailer_720p.20.flv -b 56000 -vf scale=176:144 -level 8 -vcodec mpeg4 -ab 24000 -ar 22050 -ac 1 -profile aac_low -acodec libfaac -f mp4 -y /tmp/test.mp4
ffmpeg version N-31566-gd303e0a, Copyright (c) 2000-2011 the FFmpeg developers
  built on Jul 19 2011 20:35:45 with gcc 4.4.3
  configuration: --enable-gpl --enable-version3 --enable-nonfree --enable-libfaac
  libavutil    51. 11. 0 / 51. 11. 0
  libavcodec   53.  8. 0 / 53.  8. 0
  libavformat  53.  6. 0 / 53.  6. 0
  libavdevice  53.  2. 0 / 53.  2. 0
  libavfilter   2. 27. 0 /  2. 27. 0
  libswscale    2.  0. 0 /  2.  0. 0
  libpostproc  51.  2. 0 / 51.  2. 0
[flv @ 0x260d420] Estimating duration from bitrate, this may be inaccurate

Seems stream 0 codec frame rate differs from container frame rate: 1000.00 (1000/1) -> 23.98 (24000/1001)
Input #0, flv, from 'trailer_720p.20.flv':
  Duration: 00:03:31.06, start: 0.000000, bitrate: 256 kb/s
    Stream #0.0: Video: flv, yuv420p, 1280x720, 23.98 tbr, 1k tbn, 1k tbc
    Stream #0.1: Audio: mp3, 44100 Hz, stereo, s16, 256 kb/s
[buffer @ 0x260d360] w:1280 h:720 pixfmt:yuv420p tb:1/1000000 sar:0/1 sws_param:
[scale @ 0x2610d40] w:1280 h:720 fmt:yuv420p -> w:176 h:144 fmt:yuv420p flags:0x4
Output #0, mp4, to '/tmp/test.mp4':
  Metadata:
    encoder         : Lavf53.6.0
    Stream #0.0: Video: mpeg4, yuv420p, 176x144, q=2-31, 56 kb/s, 24k tbn, 23.98 tbc
    Stream #0.1: Audio: libfaac (LC), 22050 Hz, 1 channels, s16, 24 kb/s
Stream mapping:
  Stream #0.0 -> #0.0
  Stream #0.1 -> #0.1
Press [q] to stop, [?] for help
frame= 5061 fps=141 q=2.0 Lsize=    2320kB time=00:03:31.08 bitrate=  90.0kbits/s
video:1623kB audio:619kB global headers:0kB muxing overhead 3.477867%
"	defect	closed	normal	avcodec	git-master	fixed		tfoucu@…			1	0