I am converting .ima files, collected by an audiologger, into .wav format. It works fine, but when doing this I loose the information about the date/time at which the (original, .ima) files were created. Is there a way of having the .wav files somehow 'timestamped' so I could recover the date/time at which the audio was recorded?
Many thanks for any hint provided.
As commented, you can either:
Store the date/time information in the file name
For example, store files with file names in the format 2018-09-23-19-53-45.wav, or whatever time format you like.
Store the audio in Broadcast WAV format files (BWF)
Broadcast WAV is based on WAV format but allows for metadata in the file. The difference between a Broadcast WAV file and a normal WAV is the presence of the BEXT chunk, and as such the file is compatible with existing WAV players.
The BEXT chunk contains two appropriate fields called OriginationDate and OriginationTime. The layout for the chunk can be found here: BEXT Audio Metadata Information.
Related
Is there an audio file format, where I can save all the individual chunks (recorded in javascript) while splitting them up at any point to save them to different files and have them still all playable?
Yes this is what WAV file does ... if you save the file to conform to WAV payload format you can play back the file you create as a WAV file even without file having its normal 44 byte header
I store raw audio data in arrays that can be sent to Web Audio API's AudioBuffer. The raw audio data arrays can be manipulated as you wish.
Specifics for obtaining the raw data are going to vary from language to language. I've not obtained raw data from within JavaScript. My experience comes from generating the data algorithmically or from reading .wav files with Java's AudioInputLine, and shipping the data to JavaScript via Thymefeaf.
Is there any way to find the type of stream data in the mdat of a MP4 file?
In other word how can i separate video and audio units of file?
I suppose that we don't have any headers or footers (only mdat is available).
Is PDI inefficient in terms of writing excel xlsx file with Microsoft Excel Writer.
A transformed excel data file in Pentaho output seems to be three times the size, if the data was transformed manually. Is this inefficiency expected or is there a workaround for it.
A CSV file of the same transformed output is way smaller in size. Have I configured something wrong ?
xlsx files should normally be smaller in size than CSV, since they consist of XML data compressed in ZIP files. Pentaho's Microsoft Excel Writer uses org.apache.poi.xssf.streaming.SXSSFWorkbook and org.apache.poi.xssf.usermodel.XSSFWorkbook to write xlsx files, and they create compressed files so this should not be your issue.
To check the files you could check with a zip utility, to see the file sizes and compression rate, to see if there is a bug. You could also try to open the file in Excel and re-save it, to see if that gives a smaller size, which could indicate an inefficiency.
We need to extract the volume information for every second from a video file in order to produce a graphical representation of volume changes during the video progress.
I'm trying to use FFMPEG with audio filter but I get stucked in how to extract the volume information for every second (or frame) and then export this information to some report file.
Thanks in advance.
I checked through the questions asked on SO on audio metadata, but could not find one which answers my doubt. Where exactly is the metadata of audio files stored, and in what form? Is it in the form of files or in a database? And where is this database of files stored?
Thank you Michelle. My basic confusion was whether the metadata is stored as a part of the file or in a separate file which is stored somewhere else in the file system - like inode in case of Unix like systems. ID3 shows that it is stored with the file as a block of bytes after the actual content of the file.
Is this the way of metadata storage for most of the other file types?
As far as I know, audio file formats :
May support metadata standards (e.g. ID3v1, ID3v2, APEtag, iXML)
May also have their own native metadata format (e.g. MP4 boxes / Quicktime atoms, OGG/FLAC/OPUS/Speex/Theora VorbisComment, WMA native metadata, AIFF / AIFC native metadata...)
=> In these two cases, metadata is stored directly into the audio file itself.
HydrogenAudio maintains a field mapping table between the most common formats : http://wiki.hydrogenaud.io/index.php?title=Tag_Mapping
That being said, many audio players (e.g. iTunes, foobar2000) allow their users to edit any metadata field in any file, regardless of whether said fields are supported or not by the underlying tagging standards (e.g. adding an "Album Artist" field in an S3M file).
In order to do that, these audio players store metadata in their internal database, thus giving the illusion that the audio file has been "enriched" while its actual content remain unchanged.
Another classic use of audio player databases is to store the following fields :
Rating
Number of times played
Last time played
=> In that case, you'll find metadata in the audio player's internal database