I demuxed a movie then imported the audio file into Audacity for editing, having discovered the audio was raw data. I used MediaInfo to take note of the audio file characteristics. But I don’t know what to select for “Byte order,” having to choose between “No endianness,” “Little-endian,” “Big-endian” and “Default endianness.” So far I have the following:
You are on Windows, so little endian is the obvious one to try first.
Is the raw audio from the video really 32-bit float? It seems unlikely to me. Is it really LPCM? AC3 would be more common, but you can’t import AC3 using Import Raw Audio. The “raw” designation may not mean the audio is headerless, just that it’s audio without the video.
If it’s truly raw audio data it’s just a string of bytes and I don’t think Mediainfo can tell you anything about it… Try running Mediainfo on the original audio/video file.
Most likely the audio (and video) is compressed, and “raw” compressed audio data is useless.
What’s the file size and playing time of the demultiplexed audio? There are 8 bits in a byte, so for uncompressed audio, the file size should be : File Size in kilobytes = Playing time in seconds x sample rate in kHz x (Bit Depth/8) x number of channels.
But I don’t know what to select for “Byte order,” having to choose between “No endianness,” “Little-endian,” “Big-endian” and “Default endianness.”
You’ll just have to experiment. Start with the defaults and go from there. You might want to make a chart or list to keep track of what you’ve already tried and to make sure you try them all.
If you get the sample rate wrong, you’ll get the basic sound, but the speed will be off. So, you don’t have to check all of the sample rates, at least until you hear something that sounds like audio.
Have you tried opening the audio/video file with Audacity? It can’t open the video, but with the optional FFMPEG Import/Export library, it should be able to extract the audio from almost any format.
Oops! I forgot Audacity does not encode files when importing them and selected 32 bit float because it’s the least likely to cause AV asynchrony when remuxing. I’ll change that setting to “Signed 16 bit PCM.” Attached is the log file, containing info from both MediInfo_v0.7.69 and LeeAudiBi_v0.2b, identifying the container as AAC. I have FFmpeg library installed. Movie Data.txt (4.29 KB)
…identifying the container as AAC. I have FFmpeg library installed.
So, did you try opening the movie file with Audacity (without demultiplexing first)?
There are other tools that can extract the audio from an audio/video file and create a normal WAV file (or other format). But since you already have Audacity with FFMPEG installed, let’s try that first.
Oops! I forgot Audacity does not encode files when importing them…
Normally, Audacity or FFMPEG should decode/decompress while opening, or it might give you an error if it can’t decode it or if it can’t determine the format. Of course, in the raw import mode it directly imports the raw data without decoding.
I’ll change that setting to “Signed 16 bit PCM.”
…identifying the container as AAC.
AAC is not PCM, and the raw AAC data will NOT sound like audio. Raw AAC is going to sound like noise no matter what raw settings you use to re-structure the data. And since the AAC is compressed, the raw data will probably make about a 15-minute noise file from your 2-hour movie (depending on the “raw” settings you use to structure the random noise).
You now seem to have “C:TMPMovie.2014.wav” which is AAC codec inside a WAV container, for some reason.
If that analysis is correct you will have to use FFmpeg to import that WAV file. Just drag the file into Audacity. It is not raw data as it has headers that let LeeAudiBi determine what the audio format was. It is not uncompressed audio. Import Raw Data only imports uncompressed audio.
Or as Doug says, drag the video file into Audacity. FFmpeg should extract the AAC audio and Audacity will convert/expand it to PCM 32-bit float.
I used VirtualDub to “Save WAV” that does not mean a *.wav file is saved but that with the original file extension that I assumed incorrectly is a wrapper (?) or container. Boy, I surely am a newbie. Sorry.
Anyway, your suggestion worked nicely: instead of demultiplexing, I simply dragged the movie file into Audacity and it opened up the audio, which plays and lets me edit it.