Bluecherry is hiring an Ubuntu developer!

My old employer, Bluecherry, is looking to hire an Ubuntu developer with the following experience:

• Extensive knowledge of the Video4Linux2 and ALSA sound API
  
• Prior experience in Linux based software design / implementation
  
• Prior knowledge of Ubuntu, including building / maintaining Debian packages
  
• Prior experience with gstreamer and RTSP
  
• Prior experience with MYSQL.
  
• Prior experience with Matroska file containers and video encoding
  
• Excellent verbal and written communication skills
  
• Strong knowledge of C
  
• Previous work with and understanding of working with video / audio formatting / codecs including MPEG4 and H.264
  
• Internet and operating system security fundamentals
  
• Sharp analytical abilities and proven design skills
  
• Strong sense of ownership, urgency, and drive
  
• Demonstrated ability to achieve goals in a highly innovative and fast paced environment
  

Yes it's a long list, but you are replacing me, so get used to high expectations, but a highly rewarding job. You don't need to know all of this, but you should have a good enough foundation that you can embrace the current codebase and not shy away from a steep learning curve. Visit Bluecherry's job posting for more information.

Bluecherry Releases beta1 of their new DVR product

After much delay, and much anticipation, we at Bluecherry have finally released our first public beta of version 2 of our DVR product.

For extensive details, please see the announcement.

I'm honored to have worked on this project. While I've been dealing with the driver (solo6x10) and backend server for over a year, the final parts of the product have fallen into place in just the last 6 months. It was an overwhelming effort by just 4 developers on a project that spanned from hardware to UI.

Solo6x10: Recording from video

I've finally gotten around to writing an example program for recording from Solo6x10 devices to a file. This program is very basic. It leaves the video device in it's default state (resolution, frame rate, etc). So you can modify those settings separately, and then use this program to record at those settings.

I also did not put motion detection examples in this, mainly because I have not satisfied my desire to create a decent API in v4l2 yet for that that.

Next step, I will add sound recording into this.

You can find the example source here.

To compile it, run:

gcc -lavformat bc-record.c -o bc-record

Execute it with a single command line option, the device for a solo6x10 encoder (e.g. /dev/video1). It will record until you hit ^C.

Happy recording!

Using your new Bluecherry MPEG-4 codec card and driver...

Now that the dust has settled and people are taking notice of the new driver for Bluecherry's MPEG-4 codec cards, here's a quick How-To for using it.

You will notice that there are two types of v4l2 devices created for each card. One device for the display port that produces uncompressed YUV and one for each input that produces compressed video in either MPEG-4 or MJPEG.

We'll start with the display port device. When loading the driver, a display port is created as the first device for that card. You can see in dmesg output something like this:

solo6010 0000:03:01.0: PCI INT A -> GSI 22 (level, low) -> IRQ 22
solo6010 0000:03:01.0: Enabled 2 i2c adapters
solo6010 0000:03:01.0: Initialized 4 tw28xx chips: tw2864[4]
solo6010 0000:03:01.0: Display as /dev/video0 with 16 inputs (5 extended)
solo6010 0000:03:01.0: Encoders as /dev/video1-16
solo6010 0000:03:01.0: Alsa sound card as Softlogic0

This is for a 16-port card. The output for a 4-port card would show "Encoders as /dev/video1-4" and similarly for 8-port show /dev/video1-8.

The display port allows you to view and configure what is shown on the video out port of the card. The device has several inputs and depends on which card you have installed:

• 4-port: 1 input per port and 1 virtual input for all 4 inputs in 4-up mode.
• 8-port: 1 input per port and 2 virtual inputs for 4-up on inputs 1-4 and 5-8 respectively.
• 16-port: 1 input per port and 5 virtual inputs for 4-up on inputs 1-5, 5-8, 9-12 and 13-16 and 1 virtual input for 16-up on all inputs.

You do not have to open this device for the video output of the card to work. If you open the device and set the input to input 2, and close it (without viewing any of the video) it will continue to show that input on the video out of the card. So you can simply change inputs using v4l2's ioctl's.

This is useful if you want to have live display to a CRT and use a simple program that rotates through the inputs (or multi-up virtual inputs) a few second intervals.

You can still use vlc, mplayer or whatever to view this device (you can open it multiple times).

Now for the encoder devices. There's obviously one device for each physical input on the card. The driver will allow you to record MPEG-4 and MJPEG from the same device (but you must open it twice, one for each feed). The video format cannot be configured once recording starts. So if you open the device for MPEG-4 and full D1 resultion at 30fps, that's what you're going to get if you also open a simultaneous record for MJPEG.

However, it's good to note here that MJPEG will automatically skip frames when recording. This allows you to pipe the output to a network connection (e.g. MJPEG over HTTP) with no worry of the remote connection being overloaded on bandwidth.

However, this isn't so for MPEG-4. It is possible if you are too slow at recording (not likely) to fall behind the card's internal buffer. I was not able to do this writing the full frames to disk on 44 records (4 cards of 16, 16, 8 and 4 ports).

Unlike any card before this supported by v4l2, the Bluecherry cards produce containerless MPEG-4 frames. Most v4l2 applications expect some sort of MPEG-2 stream such as program or transport. Since these programs do not expect MPEG-4 raw frames, I don't know of any that are capable of playing the encoders directly (much less being able to record from them). You can do something simple like 'cat /dev/video1' and somehow pipe it to vlc (I haven't tested this), or write a program that just writes the frames to disk (I have tested this, most programs can play the raw m4v files produced from the driver).

However, since most people will record to disk, the easiest way is to write the video frames straight out to disk.

Now on to the audio. The cards produce what is known as G.723, which is a voice codec typically found on phone systems (especially VoIP).

Since Alsa currently doesn't have a format for G.723, the driver shows it as unsigned 8-bit PCM audio. However, I can assure you that it isn't. I have sent a patch that was included in alsa-kernel (hopefully getting synced to mainline soon). But this only defines the correct format, it doesn't change the way you handle it at all.

You must convert G.723-24 (3-bit samples at 8khz) yourself. The example program I provide in my next post will show you how to do this, as well as how to convert it to MP2 audio, and record all of this to a container format on disk for later playback.

Softlogic 6010 4/8/16 Channel MPEG-4 Codec Card Driver Released

As I've talked about before, the company I work for has been dedicated to producing stable video surveillance products based on Linux.

Bluecherry's primary device for their video surveillance applications is the Softlogic based MPEG-4 codec card, which is available in 4, 8 and 16 channel models. The original driver for this card, although available as Open Source, was pretty pathetic to say the least. Most of it was just a kludge of the Windows driver, exposing all of the functionality, but with little effort to make it Linux savvy.

That's where I came in. I've since rewritten the driver so that it makes use of Linux's Video4Linux2 and Alsa driver API's. It's currently 90% functional, and many times more efficient than the original OEM driver.

Here is a quick run-down of some of the features and plus-ones against the original driver:

• Video4Linux2 interface allows easy use of existing capture software
• Alsa interface allows for easy audio capture (however, see G.723 caveats from my previous posts)
• Zero-copy in the driver. The original driver DMA'd and then copied the MPEG frames to userspace. The new driver makes use of v4l2 buffers and can DMA directly to an MMAP buffer for userspace.
• Simultaneous MPEG/MJPEG feed per channel, selectable via v4l2 format
• Standard v4l2 uncompressed video YUV display with multi-channel display format (4-up)

Now that the driver is nearing completion, it's about time to release it. I've done so via Launchpad.

• PPA Archive
• Tarball
• git clone git://git.kernel.org/pub/scm/linux/kernel/git/bcollins/solo6x10

If you are on an Ubuntu system, you can install the DKMS package from the PPA archive using these commands:

sudo add-apt-repository ppa:ben-collins/solo6x10
sudo apt-get update
sudo apt-get install solo6010-dkms

Note, I've only supplied this for Lucid right now, but if you download the .deb or the .tar.gz you should be able to install it on any recent kernel.

Review: Softlogic 6010 based MPEG-4/G.723 compression cards

So the company I work for (Bluecherry, LLC) is busy developing some products around the Softlogic 6010 based compression card. My job there has been to rewrite the driver from scratch in order to make it more Linux friendly. So to make things clear, I am writing this review from a programmer's perspective. I want to point out that I am not an MPEG expert, so I may skimp on some of the encoder details.

Let's start of with some specs. The base card supports full D1-quad compression of video into MPEG-4 video format. What this means is that it can encode 704x480 sized video at a rate of 120fps for NTSC, or 704x576 at a rate of 100fps for PAL. This breaks down to 4 full streams at 30fps and 25fps respectively. Alternately it can do CIF encoding (1/4 size of D1) at 4 times that frame rate, or for the math-lazy, 16 channels at 30fps at 320x240 frame size.

The card can be purchased in 4, 8 or 16 channel input models. So to take advantage of all 16 channels on the top model, you would either have to record in CIF mode (320x240) or reduce the frame interval to get 7.5fps per channel for full D1 mode (704x480). I will be speaking mostly in NTSC, but the card does support PAL, so do the conversions as we go.

The card allows for the usual MPEG encoding settings including GOP (Group of Pictures), Quantization and Intervals. Intervals are sort of the opposite of frames-per-second, but correlate the same way. An interval of 1 means that the encoder captures every frame, while an interval of 3 means it skips 2 frames between every frame it encodes. The video muxer on the card performs at 30fps, so the interval setting will decide how many of these frames get encoded.

The encoder itself performs quite well. It performs all encoding to an on-board SDRAM chip, and can DMA the frames directly to the host memory, which is great for performance. The original driver did not take advantage of this since it copied the frames to user space. The new driver I've written makes use of v4l2 and it's videobuf-dma-contiguous framework and thus allows for memory mapped buffers with userspace. This gives us zero-copy to userspace.

The encoder also supports side-by-side MJPEG compression of video frames. So while you can be recording the compressed MPEG-4 to disk, you can also frame grab JPEG images. This is useful for tools that want to do such frame grabbing for video analytics, or for live viewing over a web server (it's very easy to send frame grabs via an MJPEG cgi script).

All of this is built properly now on top of Linux's v4l2 API. Unfortunately the API does not expect compression cards to pipe MPEG-4 video, so most clients using v4l2 expect compressed video to be either MJPEG or MPEG-1/2 streams of some sort.

Currently the only drawback from the MPEG encoder is that the frames are self-standing MPEG-4 video frames. I have to add a header to the key frames for them to be usable by most decoders.

Overall the video capture is great. I've run 44 simultaneous records (16, 16, 8, 4 channel cards) on a Core2Duo with a system load average of 1.65, and only about 10% CPU usage. Most of the load is disk I/O.

Each encoder input also supports a graphical overlay that can be programmed at pixel level with varying colors. This is great for textual overlays. Currently we use it to place a descriptive name on the recording along with a timestamp.

In addition to the encoders, the card supports one uncompressed display port. It's currently exposed via v4l2 as a standard analog YUV device. It can be configured to show any of the inputs ports in tons of configurations. So you can do things like a 4-up display. This live display also supports a graphical overlay.

The display is sent to the video-out port on the card (hard-wired), so it can be hooked to a monitor as well (good for surveillance applications such as what Bluecherry offers).

Finally we'll discuss my least favorite part of this card. While it's not a killer, it is just odd that the card supports sound only in G.723 format. For surveillance applications this is just fine. Delivering 3-bit samples at 8Khz sample rate, which is a 24kbs. While this is good for bandwidth, it's bad for anything that needs better audio quality. Not to mention that storing the audio and video together in any sane format requires converting G.723 to linear PCM.

However, the G.723 to linear PCM conversion isn't much overhead on performance, and neither is the encoding to 16Khz MP2 audio, which is how we store it for our surveillance products. Overall, our format is MPEG-4/Video and MP2/Audio in a Matroska/mkv container. This is exactly how it was stored in my 44 stream example above.

So Pros:

• Fast and efficient
  
• Can handle multiple inputs easily
  
• The new driver works well with v4l2 and alsa
  
• Perfect for security applications
  
• Nice OSD capabilities
  
• Motion detection supported per input
  
• Side-by-side MPEG-4 and JPEG capture modes per input
  

Cons:

• MPEG-4 video. The SOLO-6110 will support H.264
  
• Low quality audio is not great for anything other than special applications (no TV DVR)
  
• G.723 audio format has been obsoleted twice since it was introduced. Nothing uses it so you must always re-encode it.