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• 'pjsip-apps/Samples' Cannot functionally run vid_streamutil.c sample

  2 décembre 2020, par ShootingKIng

  Issue Description
After building[Build Varient=Debug, Build Config=x64] the latest pjproject-vs14 (retargeted to MSVS 2017, WINSDK=8.1, because my application works at these config) as per the build instruction on trac website. Successfully built pjsua and samples.

  


  I want to use only RTP + FFMPEG APIs (pjmedia) for my application from pjproject.

  


  My config_site.h

  


  #define PJMEDIA_HAS_VIDEO           1
#define PJMEDIA_HAS_FFMPEG          1


  


  FFMPEG (pre build from ffmpeg-N-100121-g052b4c3481-win64-gpl-shared.zip)

  


  But running the example, vid_streamutil.c did not work as expected (? Whats the normal expected behaviour ?).
It says

  


  ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)


  


  To Reproduce
Steps to reproduce the behavior :

  


  

  1. run vid_streamutil.exe with parameter : --codec=H264 --remote=127.0.0.1:5000 --play-file=test.avi --send-only
(test.avi file being a sample file)

  


  


  Expected behavior
Get some RTP packets in wireshark while listening to ports 4000 and 5000 maybe ? I dont know whats the expected behaviour, documentation dosent say anything about this :(

  


  Logs/Screenshots
Couldn't catch anything on Wireshark.
Console log of vid_streamutil.exe is

  


  vid_streamutil.exe --codec=H264 --remote=127.0.0.1:5000 --send-only --play-file=test.avi
10:25:24.757 os_core_win32. !pjlib 2.10 for win32 initialized
 
10:25:24.840     wmme_dev.c  WMME found 12 devices:
10:25:24.858     wmme_dev.c   dev_id 0: Wave mapper  (in=2, out=2)
10:25:24.860     wmme_dev.c   dev_id 1: Headset Microphone (Arctis 7 Ch  (in=2, out=0)
10:25:24.860     wmme_dev.c   dev_id 2: Microphone (AMM Virtual Audio D  (in=2, out=0)
10:25:24.861     wmme_dev.c   dev_id 3: CABLE Output (VB-Audio Virtual   (in=2, out=0)
10:25:24.864     wmme_dev.c   dev_id 4: VoiceMeeter Output (VB-Audio Vo  (in=2, out=0)
10:25:24.864     wmme_dev.c   dev_id 5: Microphone (Realtek Audio)  (in=2, out=0)
10:25:24.865     wmme_dev.c   dev_id 6: Headphones (Arctis 7 Game)  (in=0, out=2)
10:25:24.866     wmme_dev.c   dev_id 7: Speakers / Headphones (Realtek   (in=0, out=2)
10:25:24.867     wmme_dev.c   dev_id 8: VoiceMeeter Input (VB-Audio Voi  (in=0, out=2)
10:25:24.884     wmme_dev.c   dev_id 9: Headset Earphone (Arctis 7 Chat  (in=0, out=2)
10:25:24.885     wmme_dev.c   dev_id 10: Speakers (AMM Virtual Audio Dev  (in=0, out=2)
10:25:24.887     wmme_dev.c   dev_id 11: Speakers (VB-Audio Virtual Cabl  (in=0, out=2)
10:25:24.887     wmme_dev.c  WMME initialized
10:25:24.890          pjlib  select() I/O Queue created (0000016B2C5F9608)
10:25:24.892 colorbar_dev.c  Colorbar video src initialized with 2 device(s):
10:25:24.915 colorbar_dev.c   0: Colorbar generator
10:25:24.935 colorbar_dev.c   1: Colorbar-active
10:25:24.956   avi_player.c  The AVI file has 2 streams.
10:25:24.976   avi_player.c  AVI file player 'test.avi' created with 2 media ports
10:25:24.994 vid_streamutil  Reading video stream 1280x720 H264 @30.00fps
10:25:25.033          rtp.c  pjmedia_rtp_session_init: ses=0000016B2C6793C8, default_pt=97, ssrc=0x294823
10:25:25.053 vstdec0000016B  Decoding channel created 720x480 I420<-H264 22/1(~22)fps
10:25:25.054          rtp.c  pjmedia_rtp_session_init: ses=0000016B2C62DF1C, default_pt=97, ssrc=0x294823
10:25:25.057 vstenc0000016B  Encoding channel created 1280x720 I420->H264 30/1(~30)fps
10:25:25.060 udp0000016B2C6  SO_RCVBUF set to 65536
10:25:25.061 udp0000016B2C6  SO_SNDBUF set to 65536
10:25:25.062   vid_stream.c  Video stream vstrm0000016B2C678508 created
10:25:25.086 vstenc0000016B  Encoder stream started
10:25:25.104 vstdec0000016B  Decoder stream paused
 [VID_STEAMUTIL] Stream is active, dir is send-only, sending to 127.0.0.1:5000
10:25:25.114 vid_streamutil  Sending 1280x720 H264 @30.00fps

Commands:
  q     Quit

Command: 10:25:25.147 ffmpeg_vid_cod !ffmpeg err -22: Invalid argument
10:25:25.222 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.237 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.250 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.251 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.287 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.311 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.316 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.341 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.353 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.369 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.386 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.387 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.411 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.415 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.452 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.469 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.486 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.496 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.506 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.527 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.547 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.568 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.576 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.604 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.606 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.627 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.648 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.668 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.686 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.711 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.731 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.752 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.769 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.778 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.804 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.827 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.833 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.868 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.886 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.895 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.921 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.923 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.943 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:25.963 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:25.983 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.003 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.019 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.038 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.041 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.060 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.081 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.086 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.109 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.130 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.138 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.162 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.183 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.202 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.220 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.228 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.260 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.281 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.312 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.321 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.321 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.322 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.323 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.323 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.324 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.324 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.333 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.353 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.353 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.381 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.401 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.414 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.429 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.449 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.469 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.480 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.510 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.531 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.553 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.571 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.594 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.615 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.636 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.653 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.671 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.678 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.714 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.736 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.754 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.777 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.781 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
10:25:26.816 ffmpeg_vid_cod  ffmpeg err -22: Invalid argument
10:25:26.836 vstenc0000016B  Codec encode_begin() error: Codec internal creation error (PJMEDIA_CODEC_EFAILED)
EOF while reading stdin, will quit now..

Commands:
  q     Quit

^C


  


  Desktop information :

  


  

  • OS, Distribution & Version : MS Windows 10 Home, 1909

  


  • PJSIP

    

    • version : 2.10

    


    • applied patch(es) : Nothing Extra

    


    • configure script params : Default

    


    • config_site.h contents : Aforementioned

    


    • related third party libraries & versions :
FFMPEG 4.3

    


    


  


  


  #define LIBAVCODEC_VERSION_MAJOR  58
#define LIBAVCODEC_VERSION_MINOR  91
#define LIBAVCODEC_VERSION_MICRO 100


  


  Additional context
I didnt change the default program that must except adding some printf's when program goes to exit label, without this it will be very difficult to know which part of the program jumped to exit : label. Anyways, here is the full code,

  


  vid_streamutil.c (with printfs)

  


  Any help is appreciated ^^'
Thanks.

  


• Server Move For multimedia.cx

  1er août 2014, par Multimedia Mike — General

  I made a big change to multimedia.cx last week : I moved hosting from a shared web hosting plan that I had been using for 10 years to a dedicated virtual private server (VPS). In short, I now have no one to blame but myself for any server problems I experience from here on out.

  The tipping point occurred a few months ago when my game music search engine kept breaking regardless of what technology I was using. First, I had an admittedly odd C-based CGI solution which broke due to mysterious binary compatibility issues, the sort that are bound to occur when trying to make a Linux binary run on heterogeneous distributions. The second solution was an SQLite-based solution. Like the first solution, this worked great until it didn’t work anymore. Something else mysteriously broke vis-à-vis PHP and SQLite on my server. I started investigating a MySQL-based full text search solution but couldn’t make it work, and decided that I shouldn’t have to either.

  Ironically, just before I finished this entire move operation, I noticed that my SQLite-based FTS solution was working again on the old shared host. I’m not sure when that problem went away. No matter, I had already thrown the switch.

  How Hard Could It Be ?
  We all have thresholds for the type of chores we’re willing to put up with and which we’d rather pay someone else to perform. For the past 10 years, I felt that administering a website’s underlying software is something that I would rather pay someone else to worry about. To be fair, 10 years ago, I don’t think VPSs were a thing, or at least a viable thing in the consumer space, and I wouldn’t have been competent enough to properly administer one. Though I would have been a full-time Linux user for 5 years at that point, I was still the type to build all of my own packages from source (I may have still been running Linux From Scratch 10 years ago) which might not be the most tractable solution for server stability.

  These days, VPSs are a much more affordable option (easily competitive with shared web hosting). I also realized I know exactly how to install and configure all the software that runs the main components of the various multimedia.cx sites, having done it on local setups just to ensure that my automated backups would actually be useful in the event of catastrophe.

  All I needed was the will to do it.

  The Switchover Process
  Here’s the rough plan :

  • Investigate options for both VPS providers and mail hosts– I might be willing to run a web server but NOT a mail server
  • Start plotting several months in advance of my yearly shared hosting renewal date
  • Screw around for several months, playing video games and generally finding reasons to put off the move
  • Panic when realizing there are only a few days left before the yearly renewal comes due

  So that’s the planning phase. BTW, I chose Digital Ocean for VPS and Zoho for email hosting. Here’s the execution phase I did last week :

  • Register with Digital Ocean and set up DNS entries to point to the old shared host for the time being
  • Once the D-O DNS servers respond correctly using a manual ‘dig’ command, use their servers as the authoritative ones for multimedia.cx
  • Create a new Droplet (D-O VPS), install all the right software, move the databases, upload the files ; and exhaustively document each step, gotcha, and pitfall ; treat a VPS as necessarily disposable and have an eye towards iterating the process with a new VPS
  • Use /etc/hosts on a local machine to point DNS to the new server and verify that each site is working correctly
  • After everything looks all right, update the DNS records to point to the new server

  Finally, flip the switch on the MX record by pointing it to the new email provider.

  Improvements and Problems
  Hosting on Digital Ocean is quite amazing so far. Maybe it’s the SSDs. Whatever it is, all the sites are performing far better than on the old shared web host. People who edit the MultimediaWiki report that changes get saved in less than the 10 or so seconds required on the old server.

  Again, all problems are now my problems. A sore spot with the shared web host was general poor performance. The hosting company would sometimes complain that my sites were using too much CPU. I would have loved to try to optimize things. However, the cPanel interface found on many shared hosts don’t give you a great deal of data for debugging performance problems. However, same sites, same software, same load on the VPS is considerably more performant.

  Problem : I’ve already had the MySQL database die due to a spike in usage. I had to manually restart it. I was considering a cron-based solution to check if the server is running and restart it if not. In response to my analysis that my databases are mostly read and not often modified, so db crashes shouldn’t be too disastrous, a friend helpfully reminded me that, “You would not make a good sysadmin with attitudes like ‘an occasional crash is okay’.”

  To this end, I am planning to migrate the database server to a separate VPS. This is a strategy that even Digital Ocean recommends. I’m hoping that the MySQL server isn’t subject to such memory spikes, but I’ll continue to monitor it after I set it up.

  Overall, the server continues to get modest amounts of traffic. I predict it will remain that way unless Dark Shikari resurrects the x264dev blog. The biggest spike that multimedia.cx ever saw was when Steve Jobs linked to this WebM post.

  Dropped Sites
  There are a bunch of subdomains I dropped because I hadn’t done anything with them for years and I doubt anyone will notice they’re gone. One notable section that I decided to drop is the samples.mplayerhq.hu archive. It will live on, but it will be hosted by samples.ffmpeg.org, which had a full mirror anyway. The lower-end VPS instances don’t have the 53 GB necessary.

  Going Forward
  Here’s to another 10 years of multimedia.cx, even if multimedia isn’t as exciting as it was 10 years ago (personal opinion ; I’ll have another post on this later). But at least I can get working on some other projects now that this is done. For the past 4 months or so, whenever I think of doing some other project, I always remembered that this server move took priority over everything else.

• Playing With Emscripten and ASM.js

  1er mars 2014, par Multimedia Mike — General

  The last 5 years or so have provided a tremendous amount of hype about the capabilities of JavaScript. I think it really kicked off when Google announced their Chrome web browser in September, 2008 along with its V8 JS engine. This seemed to spark an arms race in JS engine performance along with much hyperbole that eventually all software could, would, and/or should be written in straight JavaScript for maximum portability and future-proofing, perhaps aided by Emscripten, a tool which magically transforms C and C++ code into JS. The latest round of rhetoric comes courtesy of something called asm.js which purports to narrow the gap between JS and native code performance.

  I haven’t been a believer, to express it charitably. But I wanted to be certain, so I set out to devise my own experiment to test modern JS performance.

  Up Front Summary
  I was extremely surprised that my experiment demonstrated JS performance FAR beyond my expectations. There might be something to these claims of magnficent JS speed in numerical applications. Basically, here were my thoughts during the process :

  • There’s no way that JavaScript can come anywhere close to C performance for a numerically intensive operation ; a simple experiment should demonstrate this.
  • Here’s a straightforward C program to perform a simple yet numerically intensive operation.
  • Let’s compile the C program on gcc and get some baseline performance numbers.
  • Let’s use Emscripten to convert the C program to JavaScript and run it under Chrome.
  • Ha ! Pitiful JS performance, just as I expected !
  • Try the same program under Firefox, since Firefox is supposed to have some crazy optimization for asm.js code, allegedly emitted by Emscripten.
  • LOL ! Firefox performs even worse than Chrome !
  • Wait a minute… the Emscripten documentation mentioned using optimization levels for generating higher performance JS, so try ‘-O1′.
  • Umm… wow : Chrome’s performance increased dramatically ! What about Firefox ? Not only is Firefox faster than Chrome, it’s faster than the gcc-generated code !
  • As my faith in C is suddenly shaken to its core, I remembered to compile the gcc version with an explicit optimization level. The native C version pulled ahead of Firefox again, but the Firefox code is still close.
  • Aha ! This is just desktop– but what about mobile ? One of the leading arguments for converting everything to pure JavaScript is that such programs will magically run perfectly in mobile browsers. So I wager that this is where the experiment will fall over.
  • I proceed to try the same converted program on a variety of mobile platforms.
  • The mobile platforms perform rather admirably as well.
  • I am surprised.

  The Experiment
  I wanted to run a simple yet numerically-intensive and relevant benchmark, and something I am familiar with. I settled on JPEG image decoding. Again, I wanted to keep this simple, ideally in a single file because I didn’t know how hard it might be to deal with Emscripten. I found NanoJPEG, which is a straightforward JPEG decoder contained in a single C file.
  

  I altered nanojpeg.c (to a new file called nanojpeg-static.c) such that the main() program would always load a 1920×1080 (a.k.a. 1080p) JPEG file (“bbb-1080p-title.jpg”, the Big Buck Bunny title), rather than requiring a command line argument. Then I used gettimeofday() to profile the core decoding function (njDecode()).

  Compiling with gcc and profiling execution :

  gcc -Wall nanojpeg-static.c -o nanojpeg-static
  ./nanojpeg-static
  

  Optimization levels such as -O0, -O3, or -Os can be applied to the compilation command.

  For JavaScript conversion, I installed Emscripten and converted using :

  /path/to/emscripten/emcc nanojpeg-static.c -o nanojpeg.html \
    —preload-file bbb-1080p-title.jpg -s TOTAL_MEMORY=32000000
  

  The ‘–preload-file’ option makes the file available to the program via standard C-style file I/O functions. The ‘-s TOTAL_MEMORY’ was necessary because the default of 16 MB wasn’t enough. Again, the -O optimization levels can be sent in.

  For running, the .html file is loaded (via webserver) in a web browser.

  Want To Try It Yourself ?
  I put the files here : http://multimedia.cx/emscripten/. The .c file, the JPEG file, and the Emscripten-converted files using -O0, -O1, -O2, -O3, -Os, and no optimization switch.

  Results and Charts
  Here is the spreadsheet with the raw results.

  I ran this experiment using Ubuntu Linux 12.04 on an Intel Atom N450-based netbook. For this part, I was able to compare the Chrome and Firefox browser results against the C results :

  
  
  

  These are the results for a 2nd generation Android Nexus 7 using both Chrome and Firefox :

  
  
  

  Here is the result for an iPad 2 running iOS 7 and Safari– there is no Firefox for iOS and while there is a version of Chrome for iOS, it apparently isn’t able to leverage an optimized JS engine. Chrome takes so long to complete this experiment that there’s no reason to muddy the graph with the results :
  

  
  
  

  Interesting that -O1 tends to provide better optimization than levels 2 or 3, and that -Os (optimize for size) seems to be a good all-around choice.

  Don’t Get Too Smug
  JavaScript can indeed get amazing performance in this day and age. Please be advised, however, that this isn’t the best that a C decoder implementation can possibly do. This version doesn’t leverage any SIMD extensions. According to profiling (using gprof against the C code), sample saturation in color conversion dominates followed by inverse DCT functions, common cases for SIMD ASM or intrinsics. Allegedly, there will be some support for JS SIMD optimizations some day. We’ll see.

  Implications For Development
  I’m still not especially motivated to try porting the entire Native Client game music player codebase to JavaScript. I’m still wondering about the recommended development flow. How are you supposed to develop for Emscripten and asm.js ? From what I can tell, Emscripten is not designed as a simple aide for porting C/C++ code to JS. No, it reduces the code into JS code you can’t possibly maintain. This seems to imply that the C/C++ code needs to be developed and debugged in its entirety and then converted to JS, which seems arduous.