Mpeg2 With aac?

[daave]

Can anyone help me figure out how to encode to MPEG2 with AAC? I have FFMPEG, FCP, MPEG Streamclip, Etc. and I just can't figure it out.

[netmask56]

What format are your source files?

[daave]

Well, I have options there, too, as I can capture into various formats, so if you have suggestions, let me know. But, I thought I would capture to NTSC SD DV format using FCP.

[daave]

Anyone? Is it even possible?

[poisondeathray]

clarify your requirements - do you mean mpeg2 video in a mpeg2 program stream, with AAC audio (not AC3 audio) ?

A more typical format is mpeg2 video with AC3 audio in a mpeg2 program stream or transport stream

It might help if you described what this is for and some background information

[daave]

Thanks for your reply.

To be honest, I am not exactly sure what type of stream I need, but if you are able to advise, that would be great. I guess the big question is:

Is it possible to put MPEG2 video and AAC audio together in a single digital file?

I do not intend to burn to DVD.

I will read up on transport stream vs program stream and such in the meantime.

[poisondeathray]

Is it possible to put MPEG2 video and AAC audio together in a single digital file?

Yes it is, for example .mkv container supports this . But the question is WHY? This is a very bizzare combination - there are many more negatives than positives - lower quality video compression, poor compatiblity among them

[daave]

To further clarify, I have a project to capture Umatic and Betacam tapes to digital files. The spec is for MPEG2/AAC files. It seems like an unusual combination to me too, so I am just trying to understand it. I have Googled and such, and there just seems to be little info on how to get those two formats to stand together. Should I be asking for a better specification?

[jman98]

Is it possible to put MPEG2 video and AAC audio together in a single digital file?

Yes it is, for example .mkv container supports this . But the question is WHY? This is a very bizzare combination - there are many more negatives than positives - lower quality video compression, poor compatiblity among them

I'm puzzled by this too along with why there seems to be an explosion in the number of people who deliberately want AAC audio, even if they have to re-encode and potentially lose quality to get it.

MPEG-2 is actually capable of excellent quality provided the bit rate is high enough. And AAC is fine, but there's no advantage to it over AC3 or DTS and if anything there are some playback disadvantages to using it.

[poisondeathray]

To further clarify, I have a project to capture Umatic and Betacam tapes to digital files. The spec is for MPEG2/AAC files. It seems like an unusual combination to me too, so I am just trying to understand it. I have Googled and such, and there just seems to be little info on how to get those two formats to stand together. Should I be asking for a better specification?

Yes. There must be a mistake somewhere in your project parameters - I would get clarification

[daave]

Thanks for the replies.

So, I am going to take it back, and ask WHY the strage spec...

BUT, for the sake of this thread (because there is little info on this), can we pursue the goal of encoding a file with MPEG2 and AAC?

Specifically, I have tested poisondeathray's suggestion of encoding to MKV:

ffmpeg -y -i sample.dv -vcodec mpeg2video -sameq -acodec libfaac -sameq sample.mkv

That created a file in which both audio and video play, but when I inspect the file using MPEG Streamclip, it says:

Stream: sample.mkv
Path: /Volumes/VHStoDVD/Internal/Test/sample.mkv

Duration: 0:02:18
Data Size: 246.56 MB
Bit Rate: 14.96 Mbps

Video Tracks:
MPEG-2, 720 × 480, 29.973 fps, 9.87 Mbps

Audio Tracks:
MPEG-4 Audio stereo, 48 kHz, 44 kbps

Stream Files:
sample.mkv (4.02 MB)

The audio shows as MPEG-4. The faac library has a flag that I can use to force the version:

  --mpeg-vers X	Force AAC MPEG version, X can be 2 or 4

How do I pass that flag through from ffmpeg to the faac library?


BTW: It doesn't have to be ffmpeg; any tool you can suggest that will put MPEG2 and AAC together will be fine with me.

[poisondeathray]

eg. mkvtoolnix, there is a mac version available

or tsmuxer, if you wanted a transport stream (mac version available as well)
https://www.videohelp.com/tools/tsMuxeR

[jman98]

Thanks for the replies.

So, I am going to take it back, and ask WHY the strage spec...

What does that even mean? OK, so you don't want to answer our questions about why. That's your right. I'll just assume you're a moron. That works for me.

The audio shows as MPEG-4. The faac library has a flag that I can use to force the version:

AAC is MPEG-4 audio, so is there some reason you think this is wrong? I'm really not understanding what MPEG-4 audio would be if not AAC.

[daave]

What does that even mean? OK, so you don't want to answer our questions about why. That's your right. I'll just assume you're a moron. That works for me.

No, jman98, I am not a moron. The fact is, I did not create the spec, so I cannot answer your question immediately. I have simply been asked to do this, and I am trying to learn what I can.

AAC is MPEG-4 audio, so is there some reason you think this is wrong? I'm really not understanding what MPEG-4 audio would be if not AAC.

MPEG-2 Part 7 defines AAC as part of MPEG-2, so I don't think it is "by definition" MPEG-4 audio. While it may be true that all MPEG-4 audio is AAC, that doesn't mean that all AAC is MPEG-4 audio. I thought that MPEG Streamclip would report AAC there if it were AAC. I could be wrong...

[daave]

eg. mkvtoolnix, there is a mac version available

or tsmuxer, if you wanted a transport stream (mac version available as well)
https://www.videohelp.com/tools/tsMuxeR

Much appreciated, poisondeathray.

[El Heggunte]

Okay, just my 1.99 cents

Even though AAC was born in the MPEG-2 world so to speak, today most of us automagically think of it as an MPEG-4 thing.

Now, the boring part:

The specs say it's possible to wrap AAC in a program stream, however I'm afraid most muxers and splitters were not designed to deal with that.

Currently it's "safe" to wrap MPEG-2 video plus AAC in the following containers:

--- Matroska

--- Transport Stream

--- MP4 / MOV

--- Gabest's DSM

--- AVI (NOT Recommended)

--- ASF (NOT Recommended) (NOT Recommended)

Now, choose your destiny

[AlanHK]

To further clarify, I have a project to capture Umatic and Betacam tapes to digital files. The spec is for MPEG2/AAC files. It seems like an unusual combination to me too, so I am just trying to understand it. I have Googled and such, and there just seems to be little info on how to get those two formats to stand together. Should I be asking for a better specification?

I'll bet that it's a typo or misunderstanding.

MPEG2 + AC3 is standard. AAC is a different generation of codec.

People have responded with ways that you might be able to create this hybrid format, but I think your clients would be dumbfounded if you actually gave them what they asked for.

[daave]

All very helpfulinfo, El Heggunte, thanks.

AlanHK, you may be right!

[pandy]

MPEG container or MPEG video codec? AAC is a part of MPEG-2 standard (http://en.wikipedia.org/wiki/MPEG-2#MPEG-2_Part_7)

AAC can be stored without problems in TS container or Program Stream (MPG) container http://en.wikipedia.org/wiki/MPEG_program_stream

[bat999]

@ daave
Hi
I'm not sure you're using that "-sameq" option properly.
It's been renamed "same_quant" in modern FFmpeg builds because it means "same quantizer" NOT "same quality".
The change is documented here ---> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?p=ffmpeg.git;a=blobdiff;f=doc/avconv.te...83e13dba99480d

-same_quant
Use same quantizer as source (implies VBR).

Note that this is NOT SAME QUALITY. Do not use this option unless you know you
need it.

So maybe (when you've discussed it with the client) your command needs to be something like this:-

 ffmpeg -y -i sample.dv -c:v mpeg2video -b:v 4000k -c:a libfaac -b:a 128k sample.mkv

Change the bitrates to suit.

[daave]

So maybe (when you've discussed it with the client) your command needs to be something like this:-

 ffmpeg -y -i sample.dv -c:v mpeg2video -b:v 4000k -c:a libfaac -b:a 128k sample.mkv

Change the bitrates to suit.

ffmpeg version 0.7.11, Copyright (c) 2000-2011 the FFmpeg developers
Input #0, dv, from 'sample.dv':
  Duration: 00:08:16.02, start: 0.000000, bitrate: 28771 kb/s
    Stream #0.0: Video: dvvideo, yuv411p, 720x480, 28771 kb/s, PAR 8:9 DAR 4:3, 29.97 tbr, 29.97 tbn, 29.97 tbc
    Stream #0.1: Audio: pcm_s16le, 48000 Hz, 2 channels, s16, 1536 kb/s
Unrecognized option 'c:v'

...?

[bat999]

"Unrecognized option 'c:v'"
ffmpeg version 0.7.11 uses old syntax.
Try this instead:-

ffmpeg -y -i sample.dv -vcodec mpeg2video -b 4000k -acodec libfaac -ab 128k sample.mkv

[daave]

To follow up, I was able to put mpeg2 and aac together in a MKV file as above, suing ffmpeg. But, I explained the situation to the client and gave them 2 samples: mpeg2 with mpeg2 audio, and mpeg4 with aac.

[Cornucopia]

I would have given them a 3rd option: MPEG2 video + Ac3 audio in Mpeg2 Program stream (aka "DVD-ready"). That's most likely the kind of input they would find useful for various projects.

Scott