We are having some problems playing Wav files in RestComm: some of them play nicely but others sound very weird.
8KHz
16bit
https://www.dropbox.com/s/34mmlbopdoc3uox/record_welcome16b.wav?dl=0
Is there any place where we can consult the supported specifications of the file?
Please try with A/U Law, Sample rate of 8000Hz, bit rate of 8, Mono channels.
Related
I have a Mac app communicating with a web service that can only deal with mp3 files. I found out after hours of debugging that kAudioFormatMPEGLayer3 is decode only. So, I need to either take the resulting audio data and convert it straight to mp3 or convert it to AAC or some other supported format to mp3. Compatability with iOS is not a concern.
Also, please don't recommend LAME the license is not acceptable for this particular case. And any code demos would be greatly appreciated.
MP3 is a patented file format. You can't just write an MP3 encoder and stick it in your app unless you pay a licensing fee.
http://mp3licensing.com/royalty/
Your best bet is to stick with the built-in AAC encoding.
I know how to play mp3 files and whatnot in Xcode iOS. But how do I play a certain frequency, like if I just wanted to emit a C# note for 25 seconds; how might I do that? (The synth isn't as important to me as just the pitch of the note.)
You need to generate the PCM audio waveform that corresponds to the note you want to play and store that into a sample buffer in memory. Then you send that buffer to the audio hardware.
Here is a tutorial on generating waveforms of several types. The article goes into some details on the many aspects to a note you need to consider, including the frequency, volume, waveform shape, sampling rate, etc. The article comes with Flash source code, I think you should have no problem taking the concepts and adapting them to iOS.
If you also need a library that you can use to play the generated buffers on iOS, then I recommend the open source Finch.
I hope this helps!
You can synthesize waveforms of your desired frequency and feed them to the callbacks of either the Audio Queue or the RemoteIO Audio Unit API.
Here is a short tutorial on some of the code needed to create sine wave tones for iOS in C.
Do you know any application that will display me all the headers/parameters of a single H264 frame? I don't need to decode it, I just want to see how it is built up.
Three ways come to my mind (if you are looking for something free, otherwise google "h264 analysis" for paid options):
Download the h.264 parser from (from this thread # doom9 forums)
Download the h.264 reference software
libh264bitstream provides h.264 bitstream reading/writing
This should get you started. By the way, the h.264 bitstream is described in Annex. B. in the ITU specs.
I've created a Web version - https://mradionov.github.io/h264-bitstream-viewer/
Based on h264bitstream and inspired by H264Naked. Done by compiling h264bitstream into WebAssembly and building a simple UI on top of it. Output information for NAL units is taken from H264Naked at the moment. Also supports files of any size, just will take some time initially to load the file, but navigation throughout the stream should be seamless.
I had the same question. I tried h264 analysis, but it only supports windows. So I made a similar tool with Qt to support different platforms.Download H264Naked. This tool is essentially a wrapper around libh264bitstream
I am developing a desktop application in Adobe AIR that will be used to stream the user's camera video to a wowza media server. I want to encode the video on the fly, means transmit the H.264 encoded video instead of the default flash player encoded video for quality purpose. Is there any way around for this?
Waiting for the help from people around,
Rick
H.264 encoding is usually done in Native Code C or C++ because it is a cpu
intensive set of algorithms. The source code for x264 can give you an
idea of the code required but it is a tough read if you start from scratch.
Here is a book to get you started or you can read the original AVC standard
if you suffer from insomnia.
I'm may just be confused how this all works...in which case, please explain it to me. But, what video codecs are supported by the UPnP AV standard? Or is it on a per-device (client) basis? I want to create an app to send video data to a UPnP device (XBox, PS3, etc) but am not really sure what video codec I should target... it can be anything, I just want to know if there's a way of knowing that it will work on everything.
Edit: Ok, so I will clarify that I will be able to choose whatever video format I want, and once I do that will be all I plan on supporting, therefore I don't need transcoding. My main point was that I was hoping there was some "standard" format used that would be supported on ALL devices so that I could just pick that and be done with it... Obviously this is not the case... but is there any sort of unofficial codec that most devices support? Is there a list of devices and supported codecs anywhere?
Also, how does DLNA work into this...if I understand correctly it's sort of a subset of UPnP AV (but plus some other stuff...) And most UPnP devices I've seen are also DLNA compliant...so would just using whatever codecs DLNA supports be a way to have a common ground?
Doug is right, it depends on the client device.
You could build it so that your server transcodes files on the fly to make them available on the UPnP server, though. It would be easier just to choose a file format that is compatible with all of your devices (if the list is small enough for that to be possible).
For example, you cannot play H.264 encoded video in MKV format on Xbox 360 or PS3 right now. However, you can transcode the files to a format that IS supported. There are many of guides available online for transcoding these files for PS3/360 and what formats are supported by each device.
Here are a couple example guides:
Xbox 360 Conversion Guide
PS3 Conversion Guide
From what i understand it really depends on what codecs the device has installed - therefore it can be anything supported by your device.
I know for example that ps3 supports divx and xbox does not (unless you have windows 7 to transcode for you)
For DLAN device, some video format are must ,some are optional.
Home Devices
MUST : MPEG2
Optional :MPEG1, MPEG4, WMV9
Mobile/Handheld Devices
MUST : MPEG4 AVC (AAC LC Assoc Audio)
Optional :VC1, H.263, MPEG4 part 2, MPEG2, MPEG4 AVC (BSAC or other for Assoc. Audio)
Any other video codecs does not be mentioned here are optional , in my understanding.
check it here: