Camogm
Description
This program allows recording of the video/images acquired by Elphel 353/363 series cameras to the storage media. It is developed to use such media as hard disk drives, compact flash cards or USB storage devices (with reduced data rate as ETRAX FS processor currently supports only USB 1.1, not the fast USB 2). But it might work over the NFS and be useful even for the basic model 353 cameras that do not have any additional storage devices attached.
camogm is designed to run in the background and accept commands through a named pipe. It writes JPEG-encoded frames from the camera circbuf-circular video buffer in any of the 3 formats:
- ogm - MJPEG video in Xiph Ogg container
- jpeg - series of the individual JPEG files (1 file per frame)
- mov - MJPEG video in Apple QuickTime(R) container
As of today the last one (mov) is probably the fastest one in the camera as it uses the minimum of computational resources. Ogg is optimized for streaming and requires additional memory copying and checksum calculation for all of the recorded data, individual JPEG files grow large directories that can use system resources, while recording mov format simply merges FPGA-encoded frames (with JPEG and optional Exif headers added by the software) and the file header (with frame index) is calculated only once per file.
This program makes use of the circbuf that can hold several seconds of even high resolution/high frame rate video, so switching from file to file and/or waiting for the search operations on the HDD will not cause the frame loss - that can be verified if the Exif headers are enabled - regardless of the format selected each frame will have the exact timestamp (with 1 microsecond resolution).
Usage
Starting camogm
Eventually camogm will be started (and restarted if needed) automatically at boot time, now it is started manually with the command
camogm <named_pipe_name>
Where <named_pipe_name> is the filename that will be used to pass commands to the camogm. A good choice is "/var/state/camogm_cmd" and it is used in a camogmstate.php - a demo PHP script that can read the current status of the camogm recorder. Running camogm without any parameters or with "--help" will just output the short version of this page. So this is the example of the command that starts camogm as a background process from the shell prompt (i.e. telnet or Phpshell):
camogm /var/state/camogm_cmd &
Sending Commands to camogm
When the camogm is running you may verify that with the command:
ps | grep "camogm"
It is waiting for the commands to be sent to the pipe (/var/state/camogm_cmd above) as text strings. Commands are separated with the new lines ("\n") and/or semicolons (";"), command names are separated from the optional parameters by spaces " " and/or equal signs "=". The following is an example of such command sent from the shell prompt using command "echo" and output redirection ">" to th camogm command pipe
echo "status; exif 1; format=jpeg;status=/var/tmp/camogm.status" > /var/state/camogm_cmd
That command will:
- print current status information sending it to the standard output (may not be visible if the program was not started from the same session),
- set exif mode ON (each frame will have the full Exif header including a precise time stamp),
- set output format to a series of individual JPEG files, and then
- send status information to a file /var/tmp/camogm.status in the camera file system.
The camogmstate.php script shows how to use a named pipe for the status information so the caller will wait until camogm returns that status info (the "echo" command by itself will not wait for the status, there can (and will) be a delay between finishing of echo (or equivalent) and the appearance of the status info in the output file. With the current state of the software that status info may never come if the camera frame capture process is stopped while camogm was recording video as it checks for the new commands once per frame if it is in the "running" state (in "stopped" state in checks for the incoming commands twice a second)
camogm Commands
start
No parameters - just start recording video/images. At least two frames in the buffer are needed to start recording (they will not be lost) - the time stamp difference is used to calculate the frame rate. In the case there are not enough frames in the buffer (i.e. video acquisition is not started) the state of the camogm (reported by status and xstatus) will be "starting" before it will become "running". The video will be recorded to the same file (may be a directory for .jpeg format) until explicitly stopped, or until the specified file size/duration/number of frames is exceeded or some critical parameters (like frame dimensions) are changed. In those cases (not explicitly stopped) camogm will restart recording into a new file (filenames are composed from the specified prefix and the timestamp) so that no frames will be lost (if it is not overwhelmed by the incoming frame rate) and the first frame of a new file segment will be the next one acquired after the last one in the previous file.
stop
Just stop the recording. If you the video acquisition is on and camogm is started again before the circbuf is overrun, there will be no gaps in the recording. But if the pause will be too long some frames will be lost and there will be a gap between the next file and the previous one.
exit
Terminate camogm program (it will execute implied "stop" command first to finish recording if any).
duration
duration=<time_in_seconds>
Specify the maximal duration of each individual file segment. The new file will be started if this time limit will be exceeded. The default duration is 60 seconds, current value is reported by status/xstatus commands.
length
length=<file_size_in_bytes>
Specify the maximal size of each individual file segment in bytes. The new file will be started if this limit will be exceeded. The limit is 100000000 bytes, current value is reported by status/xstatus commands.
prefix
prefix=<file_name_prefix>
prefix value is used by the camogm to generate file names/paths to store video content. Full paths will be generated from the specified prefix, timestamps of the first frame in the segment and appropriate extension (".ogm",".jpeg" or ".mov"). The prefix consists of directory path (everything before the last slash "/") and the file name prefix (what remains after the last "/"). In the case of video formats (".ogm",".mov") the directory prefix should point to an existent directory on the mounted writeable media - camogm will not try to create missing directories and will just fail to start recording. In the case of individual JPEG files camogm will try to create the last level in directory structure if it does not exist and place all the frame files there.
exif
Controls generation and output of Exif headers for each JPEG-encoded frame. These headers slightly (for the large frames) increase the file sizes and add a little of computation to the CPU, but they are very useful for later processing as they provide precise timing information that does not depend on particular file format and timing calculations that involve frame rate and frame numbers.
exif=0
turns it off, while
exif=1
turns it on. Current default value is off, but that may change in the future so it is better to specify the desired value.
timescale
Currently only works for "mov" format (will add to "ogm" later). Values >1.0 make the video play back slower than recorded ('slow motion'), the values less than 1.0 make the playback faster (time lapse video).
frameskip
frameskip=<number_of_frames_to_skip>
Skip specified number of frames after each frame stored (default 0 - no skip)
timelapse
timelapse=<number_seconds_between_frames>
Alternative way to reduce frame rate of the recorded images - specify required image period (integer value, in seconds). All intermediate images will be skipped, only first after each multiple of the specified interval will be stored. That means, that the time interval between subsequent images maybe slightly different, but the rounding error will not accumulate during long recordings.
timelapse and frameskip are mutually exclusive (they even use the same variable with positive values for frame skip (in frames) and negative - timelapse (in seconds).
format
format=[ogm|jpeg|mov]
- ogm - record video as Ogg Media Stream
- jpeg - record video as a series of JPEG files
- mov - record video as Apple Quicktime (R) files
reset
Mostly a debug feature. Force camogm to start next file from the two most recent images in the circbuf, discarding all the older ones. It is the same action camogm does when the buffer is overrun and frames are lost.
debug
debug debug=<file>
The first command form (with to file specified) turns the debug output off, the second - directs it somewhere. camogm recognizes several special names like "stdout" and "stderr", it also treats file name "none", "null" and "/dev/null" as empty and turns the debug feature off.
debuglev
debuglev=<integer_value>
Allows to specify debug verbosity level, the higher the level the more information is output (it may slow down camogm and cause it to drop frames even if it could handle it with no/low debug output).
save_gp
save_gp=[0|1]
As a debug feature camogm can set the camera global circbuf read pointer to the current value of camogm's read pointer. In that case it is possible to watch the camogm progress by other programs, such as imgsrv
status
status status=<status_output_file>
This command provides the current camogm state information and sends it to standard output (maybe invisible if camogm was started from different shell session or by other means) or to the specified output file in plain text format. The same information is available in XML format - see xstatus command below. The following is a commented sample output generated by the status command:
state running // may be stopped, running and starting. Usually the last
// one can be only visible if there are no images coming to the buffer.
file /tmp/z/qvid1195433980_662716.mov // full path toi the current file being recorded
frame 293 // current frame number (starts from 0)
file duration 14.616060 sec // current duration of the video in this file segment
file length 13167561 B // current video file size
frame period 50055 (0xc387) // frame period in microseconds (this one is approximately 1/20 sec)
frames to skip 100 (left 37) // number of frames to skip after the frame is acquired. Shown only if frame skip mode is enabled.
timelapse period 10 sec (remaining 10 sec) // frame period for time lapse mode (time till next frame will be stored). Shown only if time lapse mode enabled
width 1024 (0x400) // frame width in pixels
height 768 (0x300) // frame height in pixels
// - blank line
output format mov // output file format - one of "ogm", "jpeg" and "mov"
using exif yes // frames are generated with Exif headers that include time stamps
path prefix: /tmp/z/qvid // file prefix as specified in prefix command
max file duration: 60 sec // maximal file duration as specified in duration command
max file length: 100000000 B // maximal file length as specified in length command
max frames 16384 // maximal number of frames as specified in ... none yet, uses default
timescale 1.000000 // time scale as specified in timescale command
frames per chunk 10 // "frames per chunk" used in "mov" format
// - blank line
buffer overruns 0 // number of buffer overruns while recording since last status/xstatus
// (these commands zero the buffer overruns counter). If no overruns
// are reported, no frames are lost, including between file segments.
buffer minimal 19748288 // Minimal level of the buffer memory since last status/xstatus command.
buffer free 19748192 // Current amount of free memory in the video buffer (actual value might
// be one frame less as the FPGA write pointer is reported only after
// the whole frame is stored
buffer used 43680 // Amount of memory currently used in the video buffer.
circbuf_rp 10933536 (0xa6d520) // Current location of the read pointer in the video buffer
// - blank line
debug output to stderr // where the debug messages are sent to (as specified in debug command)
debug level 1 // Debug verbosity level, the higher - the more "noisier". Set in
// debuglev command.
use global pointer no // see save_gp command.
"-1" values that status/xstatus commands may return for some parameters mean "undefined", they are calculated only during video recording.
xstatus
status status=<status_output_file>
Same information as described for status command above, but presented in XML format more suitable to be processed by other software while status is easier to read by humans. See camogmstate.php PHP script that returns this XML data to the HTTP GET requests.
<?xml version="1.0"?> <camogm_state> <state>"running"</state> <file_name>"/tmp/z/qvid1195440137_027276.mov"</file_name> <frame_number>281</frame_number> <file_duration>14.015400</file_duration> <file_length>12731197</file_length> <frame_period>50055</frame_period> <frames_skip>0</frames_skip> <seconds_skip>10</seconds_skip> <frames_skip_left>0</frames_skip_left> <seconds_skip_left>7</seconds_skip_left> <frame_width>1024</frame_width> <frame_height>768</frame_height> <format>"mov"</format> <exif>"yes"</exif> <prefix>"/tmp/z/qvid"</prefix> <max_duration>60</max_duration> <max_length>100000000</max_length> <max_frames>16384</max_frames> <timescale>1.000000</timescale> <frames_per_chunk>10</frames_per_chunk> <buffer_overruns>0</buffer_overruns> <buffer_minimal>19747712</buffer_minimal> <buffer_free>19747808</buffer_free> <buffer_used>44064</buffer_used> <circbuf_rp>16275392</circbuf_rp> <debug_output>"stderr"</debug_output> <debug_level>1</debug_level> <use_global_rp>"no"</use_global_rp> </camogm_state>
This program does not control the process of acquisition of the video/images to the camera internal buffer, it only retrieves that data from the buffer (waiting when needed), packages it to selected format and stores the result files.
Camogm2
This is modified version of camogm to support audio recording. It support recording of audio 16bit mono/stereo, from 11025 to 44100 Hz to QuickTime(MOV) and OGG(OGM) file formats. Source of the audio is the sound card (can be connected to camera over USB), and file storage can be USB-flash, HDD (connected to camera directly) or NFS-mounted disk. Preferred method is HDD drive, connected to camera directly, because NFS-mounted disk have a non-uniform system load what can cause broken files.
The recorded movie have the same duration of the video and sound, but when play it's depend on how player work with file - for example, QuickTime player play movie like the sound is shorter than video, MPlayer will repeat the last sound piece at the end of movie etc. - so it's better to merge movie from the chunks to single movie.
P.S. First check the sound hardware: make an upload of some test WAVE file to camera at /tmp/ folder, set volume to maximum by command
amixer set PCM 100
and try to play uploaded test sound file:
aplay /tmp/test_file_name.wav
- if you can't hear any sound, probably you have an old USB card on the camera - this new 10349 RevC will work correctly with sound card.
camogm2 Commands
audio
audio=<on|off>
command to enable or disable audio recording. When audio support is disabled, camogm work in the same way as original camogm. By default audio is disabled.
audio_format
audio_format=<[rate][/channels]>
command to set audio format - frame rate and number of channels. Frame rate can be from 11025 to 44100 Hz; number of channels - 1 for mono sound, or 2 - for stereo. By default 44100/2
allow_sync
allow_sync=<enable|disable>
setting for sync mode - to use it with NFS mounted disk. By default disabled.
