Add audio track to M4V that already has a variable number of audio tracks

[ppomes]

I want to make all my movies on an external drive playable on the Roku 3. The complication is that most of the files contain a variable number of audio tracks (main, director's commentary, perhaps a second language track, etc), and +/- subtitle tracks.

I've selected all the .mkv and .m4v files with AC3-only audio, extracted the first audio track, and created the AAC equivalent. To add the new AAC audio track to the .mkv files I use "mkvmerge -o new-movie.mkv movie.mkv movie.aac". How do I accomplish this with ffmpeg (or other program with a CLI) for the .m4v files and not clobber any of the existing tracks? My usual OS is Linux, however Windows 7 is available as well.

Thank you in advance.

[ppomes]

I found the initial answer to my question with the command

ffmpeg -i movie.m4v -i movie.aac -c copy -map 0 -map 1 new-movie.m4v

where movie.aac was generated with the commands

ffmpeg -i movie.m4v -map 0:a:0 -vn -acodec copy movie.ac3
ffmpeg -i movie.ac3 -acodec libfaac movie.aac

The result of the first command is

    [...]
    Stream #0:0(und): Video: h264 (avc1 / 0x31637661), yuv420p, 718x480 [SAR 8:9 DAR 359:270], q=2-31, 1340 kb/s, 23.98 fps, 23.98 tbr, 90k tbn, 90k tbc (default)
    Metadata:
      creation_time   : 2014-05-14 14:08:36
      encoder         : JVT/AVC Coding
    Stream #0:1(eng): Audio: ac3 (ac-3 / 0x332D6361), 48000 Hz, 5.1(side), 384 kb/s (default)
    Metadata:
      creation_time   : 2014-05-14 14:08:36
    Side data:
      unknown side data type 7 (4 bytes)
    Stream #0:2(und): Subtitle: mov_text (text / 0x74786574)
    Metadata:
      creation_time   : 2014-05-14 14:08:36
    Stream #0:3: Audio: aac (mp4a / 0x6134706D), 48000 Hz, 5.1, 195 kb/s
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
  Stream #0:2 -> #0:2 (copy)
  Stream #1:0 -> #0:3 (copy)
Press [q] to stop, [?] for help
[ipod @ 0x1bd29e0] Malformed AAC bitstream detected: use the audio bitstream filter 'aac_adtstoasc' to fix it ('-bsf:a aac_adtstoasc' option with ffmpeg)
av_interleaved_write_frame(): Operation not permitted
frame= 1961 fps=0.0 q=-1.0 Lsize=   15962kB time=00:01:21.88 bitrate=1596.8kbits/s    
video:12060kB audio:3839kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.395979%
Conversion failed!

Adding '-bsf:a aac_adtstoasc'

ffmpeg -i movie.m4v -i movie.aac -c copy -bsf:a aac_adtstoasc -map 0 -map 1 new-movie.m4v

doesn't exactly help:

[...]
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
  Stream #0:2 -> #0:2 (copy)
  Stream #1:0 -> #0:3 (copy)
Press [q] to stop, [?] for help
[NULL @ 0x2732500] Error parsing ADTS frame header!
Failed to open bitstream filter aac_adtstoasc for stream 0 with codec copy: Invalid data found when processing input
[NULL @ 0x2732500] Error parsing ADTS frame header!
Failed to open bitstream filter aac_adtstoasc for stream 0 with codec copy: Invalid data found when processing input
[NULL @ 0x2732500] Error parsing ADTS frame header!
Failed to open bitstream filter aac_adtstoasc for stream 0 with codec copy: Invalid data found when processing input
[...]

There's not much help via Google in resolving these errors. Anyone have an alternate approach?

Thanks.

[ppomes]

Found the solution, use a mp4 container for the AAC file. This assumes the AC3 track is the first audio track.

ffmpeg -i movie.m4v -map 0:a:0 -vn -acodec libfaac movie.mp4
ffmpeg -i movie.m4v -i movie.mp4 -c copy -map 0 -map 1 new-movie.m4v

Hopefully this thread will prove useful to someone else.

[Baldrick]

Thanks for posting the solution!

[ndjamena]

mp4box -add movie.m4v -add "movie.aac:lang=en:group=1:name=AAC Audio" movie-new.m4v

[ppomes]

Here's the Readme file I created to help me the next time I have to do this and the painfully gathered knowledge has evaporated. It's not meant to be used in a "fire and forget" mode. I cut and paste the shell fragments, run each individually, verify the results, then go on to the next step.

Cheers!

Paul Pomes, DVM
http://www.FurryFriendsVet.com

# AAC-from-AC3
#
# My Roku 3 does not support the AC-3 audio codec. To make all my movies
# playable I've created this set of scripts to extract the AC-3 track from
# movies that lack an AAC track, convert that to AAC, and layer it back into
# the MKV or M4V container as an additional track while preserving all
# existing tracks.

# This collection of scripts generates action scripts. I'm cautious about
# overly-automating conversions since a mistake could trash a lot of effort.
# Backups are an excellent idea, however mine are currently on CONUS while
# I'm working on Guam with a USB drive copy. Once the action scripts are
# created, I test them on a single movie to make sure the results are what
# I intend before letting it go full-auto on the rest.
#
# Paul Pomes, DVM
# paul@pomes.org
# www.FurryFriendsVet.com

# Identify which files lack an AAC track

rm -i mkv-files m4v-files

for i in *mkv
do
	mediainfo "$i" | grep -q AAC
	if [ $? -ne 0 ] ; then echo $i >> mkv-files ; fi
done

for i in *m4v
do
	mediainfo "$i" | grep -q AAC
	if [ $? -ne 0 ] ; then echo $i >> m4v-files ; fi
done

# Identify which audio track is the main AC-3 track. Almost always this will be
# track 1. Exceptions - say it's track 3 - can be handled by hand edits of
# the extraction scripts. For MKV files change "1:[...]" to "3:[...]"
# (see examples below). For M4V change "-map 0:a:0" to "-map 0:a:2".

# Create extraction and conversion scripts. First is for MKV containers,
# the second for M4V. AC-3 to AAC is the slowest part of this whole process
# which for 40 movies took overnight.

while read i
do
	j=`basename -s .mkv "$i"`
	echo -n "mkvextract tracks \"$i\" "
	mkvmerge -i "$i" | grep AC3 | head -1 | sed -e "s/.*\(.\):.*/\1:\"$j.ac3\" ; \\\\ /"
	echo "ffmpeg -i \"$j.ac3\" -acodec libfaac \"$j.aac\""
done < mkv-files

while read i
do
	j=`basename -s .m4v "$i"`
	echo -n "ffmpeg -i \"$i\" -map 0:a:"
	echo -n $((`mkvmerge -i "$i" | grep AC3 | head -1 | sed -e "s/.*\(.\):.*/\1/"` - 1))
	echo " -vn -acodec libfaac \"$j.mp4\""
done < m4v-files

# Mux the new AAC files into the original containers
while read i
do
	j=`basename -s .mkv "$i"`
	k="$j-new.mkv"
	echo "mkvmerge -o \"$k\" \"$i\" \"$j.aac\""
	echo "ls -lh \"$k\" \"$i\""
	echo "mkvmerge -i \"$i\""
	echo "mkvmerge -i \"$k\""
	echo "mv -i \"$k\" \"$i\""
done < mkv-files

while read i
do
	j=`basename -s .m4v "$i"`
	k="$j-new.m4v"
	echo "ffmpeg -i \"$i\" -i \"$j.mp4\" -c copy -map 0 -map 1 \"$k\""
	echo "ls -lh \"$k\" \"$i\""
	echo "mkvmerge -i \"$i\""
	echo "mkvmerge -i \"$k\""
	echo "mv -i \"$k\" \"$i\""
done < m4v-files