Rewrap using ffmbc and 5.1 audio

[SameSelf]

Can someone please tell me if ffmbc can handle rewrapping 5.1/6 channel AC3 audio into a Quicktime container using AAC audio? For example, if I have an MP4 with stereo AC3, the following works like a charm:

ffmbc -i input.MTS -vcodec copy -acodec aac -ab 256k -strict experimental input.mov

However, if the video contains 5.1/6 channel AC3 audio, the code above chokes hard. One work around I have found is to just demux the TS.

ffmbc -i input.MTS -vcodec copy -an input.mov
ffmbc -i input.MTS -vn output.wav

But, I am really hoping that I can find a way around that using ffmbc. FFmbc seems to be the preferred tool for rewrapping AVCHD according to https://code.google.com/p/ffmbc/. I am building my Swiss army knife of tools and any help would be appreciated

[TorBru]

"Chokes" how? Why would you reencode the AC3 audio? Have you tried with ffmpeg? Your MTS might have multiple audio streams and you are not specifying which to use - could this be the problem?

[poisondeathray]

Yes, it crashes. It probably can't do 6ch audio with aac

You could use ffmpeg to do it (it doesn't crash), but there is something "magical" about ffmbc's muxing that makes things go smoother in programs like NLE's

If space is not an issue, use uncompressed audio
ffmbc -i INPUT.mts -vcodec copy -acodec pcm_s16le OUTPUT.mov

or You could do it as a 2 step batch file, using a better aac encoder , like QAAC or NeroAAC, by piping ffmbc to it, and muxing that output with stream copied video. You usually don't want to use ffmpeg / ffmbc's AAC encoders (libvo_aacenc , faac, libfaac, etc...) anyways (quality is quite poor) . Although you can build ffmpeg/ffmbc with libfdk_aac, they are not distributed with it because of licensing /legal issues. The "best" AAC encoders are probably quicktime (QAAC), FDK_AAC, or NeroAAC

[SameSelf]

"Chokes" how? Why would you reencode the AC3 audio? Have you tried with ffmpeg? Your MTS might have multiple audio streams and you are not specifying which to use - could this be the problem?

Chokes as in:



I have tried ffmpeg and it works but as I mentioned in my OP, ffmbc seems to be the preferred tool for rewrapping AVCHD to Quicktime per https://code.google.com/p/ffmbc/. However, you are correct that my MTS has multiple audio streams. As I mention in the title, my video is 5.1/6 channel AC3 audio. And trying to convert that to AAC causes the crash above.

Yes, it crashes. It probably can't do 6ch audio with aac

You could use ffmpeg to do it (it doesn't crash), but there is something "magical" about ffmbc's muxing that makes things go smoother in programs like NLE's

If space is not an issue, use uncompressed audio
ffmbc -i INPUT.mts -vcodec copy -acodec pcm_s16le OUTPUT.mov

or You could do it as a 2 step batch file, using a better aac encoder , like QAAC or NeroAAC, by piping ffmbc to it, and muxing that output with stream copied video. You usually don't want to use ffmpeg / ffmbc's AAC encoders (libvo_aacenc , faac, libfaac, etc...) anyways (quality is quite poor) . Although you can build ffmpeg/ffmbc with libfdk_aac, they are not distributed with it because of licensing /legal issues. The "best" AAC encoders are probably quicktime (QAAC), FDK_AAC, or NeroAAC

I see I am not the only one who gets crashes. But, I am glad to hear I wasn't on the wrong path when you say there is something "magical" about ffmbc.

Thanks for the heads up on the best AAC encoders. I am learning as I go and always marvel at your in depth knowledge. Looks like that is the path I need to take. I have zero experience when it comes to creating my own builds for ffmpeg. Although I may be posting back here with instructions on how to mux using ffmbc. We'll see how it goes. Thanks!

[poisondeathray]

However, you are correct that my MTS has multiple audio streams. As I mention in the title, my video is 5.1/6 channel AC3 audio.

It has multiple audio channels, not streams, correct ? "multiple streams" implies multiple audio tracks. So not 1 * 6 ch, but maybe several

The basic syntax for 1 video using qaac might look something like this , and you can probably convert it to a batch

"ffmbc.exe" -i INPUT.mts -vn -acodec pcm_s16le -f wav - | "qaac.exe" --cbr 384k --no-delay -o qaac384k.mp4 -
"ffmbc.exe" -i INPUT.mts -i qaac384k.mp4 -map 0:0 -map 1:0 -vcodec copy -acodec copy OUTPUT.mov
del qaac384k.mp4

[SameSelf]

Thanks for the code examples. I have to be honest I don't know if I have multiple channels or streams. Looks like I need to edumacate myself about these things some more

[SameSelf]

Streams or channels? I don't know for sure. I can only tell you what Mediainfo tells me. So based on the below, it looks like six channels in one audio stream, correct?

Audio
ID                                       : 4352 (0x1100)
Menu ID                                  : 1 (0x1)
Format                                   : AC-3
Format/Info                              : Audio Coding 3
Mode extension                           : CM (complete main)
Format settings, Endianness              : Big
Codec ID                                 : 129
Duration                                 : 2mn 42s
Bit rate mode                            : Constant
Bit rate                                 : 448 Kbps
Channel(s)                               : 6 channels
Channel positions                        : Front: L C R, Side: L R, LFE
Sampling rate                            : 48.0 KHz
Bit depth                                : 16 bits
Compression mode                         : Lossy
Delay relative to video                  : -67ms
Stream size                              : 8.66 MiB (5%)

[poisondeathray]

Yes, that is 6ch , 1 track (or stream)