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• Ubuntu12.04 : libavformat header trouble when compiling C program

  30 mai 2013, par Juneyoung Oh

  My code is super simple, just include "avformat.h" and call "av_register_all".

  full code is below.

    1 #include 
  
    2 #include 
  
    3 #include 
  
    4 //#include <libavcodec></libavcodec>avcodec.h>
  
    5 #include <libavformat></libavformat>avformat.h>
  
    6 //#include "libavcodec/avcodec.h"
  
    7 //#include "libavformat/avformat.h"
  
    8 
  
    9 
  
   10 int main (int argc, char* argv[]){
  
   11         av_register_all();
  
   12 /*
  
   13         AVFormatContext* pFormatCtx;
  
   14         const char* filename = "/home/juneyoungoh/Videos/CON1234ID.ts";
  
   15 
  
   16         if(av_open_input_file(&amp;pFormatCtx, filename, NULL, 0, NULL) != 0)
  
   17         {
  
   18                 handle_error();
  
   19         }
  
   20 
  
   21         if(av_find_stream_info(pFormatCtx) &lt; 0)
  
   22         {
  
   23                 handle_error();
  
   24         }
  
   25 
  
   26         dump_format(pFormatCtx, 0, filename, 1);
  
   27 
  
   28         //av_get_audio_frame_duration();
  
   29 */
  
   30         return 0;
  
   31 }

  The problem is when I compile this in Terminal it show error.

  /tmp/ccvgpGjv.o: In function `main':
  
  getDuration.c:(.text+0x10): undefined reference to `av_register_all'
  
  collect2: ld returned 1 exit status

  my avformat.h file is in /usr/local/include/libavformat/avformat.h.

  Here is something I have already tried.

  1. gcc getDuration.c
  2. gcc -I/usr/local/include/ getDuration.c
  3. gcc -I/usr/local/include/libavformat/ getDuration.c
  4. gcc -L/usr/local/include/ getDuration.c
  5. gcc -L/usr/local/include/libavformat/ getDuration.c
  6. gcc getDuration.c -lavformat

  Give me the light of hope +_+

• Getting ffserver && ffmpeg to work of Debian with Logitech C270 [closed]

  14 mars 2013, par Joseph Baldwin Roberts

  I'm having real trouble getting my webcam to work and I wonder if anyone can help. Im running Raspian on a raspberry pi.

  When I run lsusb I get :

  pi@raspberrycar ~ $ lsusb
  
  Bus 001 Device 002: ID 0424:9512 Standard Microsystems Corp.
  
  Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
  
  Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp.
  
  Bus 001 Device 004: ID 05e3:0608 Genesys Logic, Inc. USB-2.0 4-Port HUB
  
  Bus 001 Device 005: ID 0bda:8176 Realtek Semiconductor Corp. RTL8188CUS 802.11n WLAN Adapter
  
  Bus 001 Device 006: ID 046d:0825 Logitech, Inc. Webcam C270

  When I run v412-ctl —all I get :

  pi@raspberrycar ~ $ v4l2-ctl --all
  
  Driver Info (not using libv4l2):
  
          Driver name   : uvcvideo
  
          Card type     : UVC Camera (046d:0825)
  
          Bus info      : usb-bcm2708_usb-1.2.4
  
          Driver version: 3.6.11
  
          Capabilities  : 0x04000001
  
                  Video Capture
  
                  Streaming
  
  Format Video Capture:
  
          Width/Height  : 640/480
  
          Pixel Format  : 'YUYV'
  
          Field         : None
  
          Bytes per Line: 1280
  
          Size Image    : 614400
  
          Colorspace    : SRGB
  
  Crop Capability Video Capture:
  
          Bounds      : Left 0, Top 0, Width 640, Height 480
  
          Default     : Left 0, Top 0, Width 640, Height 480
  
          Pixel Aspect: 1/1
  
  Video input : 0 (Camera 1: ok)
  
  Streaming Parameters Video Capture:
  
          Capabilities     : timeperframe
  
          Frames per second: 5.000 (5/1)
  
          Read buffers     : 0

  When I run v412-ctl —list-formats I get :

  pi@raspberrycar ~ $ v4l2-ctl --list-formats
  
  ioctl: VIDIOC_ENUM_FMT
  
          Index       : 0
  
          Type        : Video Capture
  
          Pixel Format: 'YUYV'
  
          Name        : YUV 4:2:2 (YUYV)
  
  
  
          Index       : 1
  
          Type        : Video Capture
  
          Pixel Format: 'MJPG' (compressed)
  
          Name        : MJPEG

  My ffserver settings file is /etc/ffserver.conf

  Port 80
  
  BindAddress 0.0.0.0
  
  MaxClients 10
  
  MaxBandwidth 50000
  
  NoDaemon
  
  
  
  <feed>
  
  file /tmp/webcam.ffm
  
  FileMaxSize 10M
  
  </feed>
  
  
  
  <stream>
  
  Feed webcam.ffm
  
  Format mpeg
  
  VideoSize 640x480
  
  VideoFrameRate 10
  
  VideoBitRate 2000
  
  VideoQMin 1
  
  VideoQMax 10
  
  </stream>
  
  
  
  <stream>
  
  Format status
  
  
  
  ACL allow 192.168.2.0 192.168.2.255
  
  </stream>

  My ffmpeg run string is /usr/sbin/webcam.sh

  ffserver -f /etc/ffserver.conf & ffmpeg -v verbose -r 5 -s 640x480 -f video4linux2 -i /dev/video0 http://localhost/webcam.ffm

  When I run this is the output :

  pi@raspberrycar ~ $ sudo /usr/sbin/webcam.sh
  
  ffmpeg version 1.0.5ffserver version 1.0.5 Copyright (c) 2000-2012 the FFmpeg developers
  
    built on Mar 14 2013 18:37:40 with gcc 4.6 (Debian 4.6.3-14+rpi1)
  
   Copyright (c) 2000-2012 the FFmpeg developers
  
    built on Mar 14 2013 18:37:40 with gcc 4.6 (Debian 4.6.3-14+rpi1)
  
    configuration:
  
    libavutil      51. 73.101 / 51. 73.101
  
    configuration:
  
    libavutil      51. 73.101 / 51. 73.101
  
    libavcodec     54. 59.100 / 54. 59.100
  
    libavformat    54. 29.104 / 54. 29.104
  
    libavdevice    54.  2.101 / 54.  2.101
  
    libavfilter     3. 17.100 /  3. 17.100
  
    libswscale      2.  1.101 /  2.  1.101
  
    libavcodec     54. 59.100 / 54. 59.100
  
    libavformat    54. 29.104 / 54. 29.104
  
    libavdevice    54.  2.101 / 54.  2.101
  
    libavfilter     3. 17.100 /  3. 17.100
  
    libswscale      2.  1.101 /  2.  1.101
  
    libswresample   0. 15.100 /  0. 15.100
  
    libswresample   0. 15.100 /  0. 15.100
  
  [video4linux2,v4l2 @ 0xfa5620] [3]Capabilities: 4000001

  I can see the stream on the status page and my webcam light is on but it never loads. Does anyone know what I am doing wrong ?

  Thanks in advance

  Joe

• Elacarte Presto Tablets

  14 mars 2013, par Multimedia Mike — General

  I visited an Applebee’s restaurant this past weekend. The first thing I spied was a family at a table with what looked like a 7-inch tablet. It’s not an uncommon sight. However, as I moved through the restaurant, I noticed that every single table was equipped with such a tablet. It looked like this :

  
  
  

  For a computer nerd like me, you could probably guess that I was be far more interested in this gadget than the cuisine. The thing said “Presto” on the front and “Elacarte” on the back. Putting this together, we get the website of Elacarte, the purveyors of this restaurant tablet technology. Months after the iPad was released on 2010, I remember stories about high-end restaurants showing their wine list via iPads. This tablet goes well beyond that.

  How was it ? Well, confusing, mostly. The hostess told us we could order through the tablet or through her. Since we already knew what we wanted, she just manually took our order and presumably entered it into the system. So, right away, the question is : Do we order through a human or through a computer ? Or a combination ? Do we have to use the tablet if we don’t want to ?

  Hardware
  When picking up the tablet, it’s hard not to notice that it is very heavy. At first, I suspected that it was deliberately weighted down as some minor attempt at an anti-theft measure. But then I remembered what I know about power budgets of phones and tablets– powering the screen accounts for much of the battery usage. I realized that this device needs to drive the screen for about 14 continuous hours each day. I.e., the weight must come from a massive battery.

  The screen is good. It’s a capacitive touchscreen, so nice and responsive. When I first spied the device, I felt certain it would be a resistive touchscreen (which is more accurately called a touch-and-press-down screen). There is an AC adapter on the side of the tablet. This is the only interface to the device :

  
  
  

  That looks to me like an internal SATA connector (different from an eSATA connector). Foolishly, I didn’t have a SATA cable on me so I couldn’t verify.

  User Interface
  The interface options are : Order, Games, Neighborhood, and Pay. One big benefit of accessing the menu through the Order option is that each menu item can have a picture. For people who order more by picture than text description, this is useful. Rather, it would be, if more items had pictures. I’m not sure there were more pictures than seen in the print menu.
  
  For Games, there were a variety of party games. The interface clearly stated that we got to play 2 free games. This implied to me that further games cost money. We tried one game briefly and the food came.

  2 more options : Neighborhood– I know I dug into this option, but I forget what it was. Maybe it discussed local attractions. Finally, Pay. This thing has an integrated credit card reader. There is no integrated printer, though, so if you want one, you will have to request one from a human.

  Experience
  So we ordered through a human since we didn’t feel like being thrust into this new paradigm when we just wanted lunch. The staff was obviously amenable to that. However, I got a chance to ask them a lot of questions about the particulars. Apparently, they have had this system for about 5 months. It was confirmed that the tablets do, in fact, have gargantuan batteries that have to last through the restaurant’s entire business hours. Do they need to be charged every night ? Yes, they do. But how ? The staff described this several large charging blocks with many cables sprouting out. Reportedly, some units still don’t make it through the entire day.

  When it was time to pay, I pressed the Pay button on the interface. The bill I saw had nothing in common with what we ordered (actually, it was cheaper, so perhaps I should have just accepted it). But I pointed it out to a human and they said that this happens sometimes. So they manually printed my bill. There was a dollar charge for the game that was supposed to be free. I pointed this out and they removed it. It’s minor, I know, but it’s still worth trying to work out these bugs.

  One of the staff also described how a restaurant doesn’t need to employ as many people thanks to the tablet. She gave a nervous, awkward, self-conscious laugh when she said this. All I could think of was this Dilbert comic strip in which the boss realizes that his smartphone could perform certain key functions previously handled by his assistant.

  Not A New Idea
  Some people might think this is a totally new concept. It’s not. I was immediately reminded of my university days in Boulder, Colorado, USA, circa 1997. The local Taco Bell and Arby’s restaurants both had touchscreen ordering kiosks. Step up, interact with the (probably resistive) touchscreen, get a number, and step to the counter to change money, get your food, and probably clarify your order because there is only so much that can be handled through a touchscreen.

  What I also remember is when they tore out those ordering kiosks, also circa 1997. I don’t know the exact reason. Maybe people didn’t like them. Maybe there were maintenance costs that made them not worth the hassle.

  Then there are the widespread self-checkout lanes in grocery stores. Personally, I like those, though I know many don’t. However, this restaurant tablet thing hasn’t won me over yet. What’s the difference ? Perhaps that automated lanes at grocery stores require zero external assistance– at least, if you do everything correctly. Personally, I work well with these lanes because I can pretty much guess the constraints of the system and I am careful not to confuse the computer in any way. Until they deploy serving droids, or at least food conveyors, there still needs to be some human interaction and I think the division between the human and computer roles is unintuitive in the restaurant case.

  I don’t really care to return to the same restaurant. I’ll likely avoid any other restaurant that has these tablets. For some reason, I think I’m probably supposed to be the ideal consumer of this concept. But the idea will probably perform all right anyway. Elacarte’s website has plenty of graphs demonstrating that deploying these tablets is extremely profitable.