Search Results

Search found 33 results on 2 pages for 'huffman'.

Page 1/2 | 1 2  | Next Page >

• Confused about Huffman Trees

  - by ShrimpCrackers

  A quick tutorial on generating a huffman tree Confused about Huffman Trees. Near the end of that link above, it shows the tree with 2 elements left, and then the completed tree. I'm confused about the way that it is branched. Is there a specific way a huffman tree needs to be branched? For example, 57:* with its right child 35:* is branched off to the right. Could it have been 35 branched to the left with 22 branched to the right? Also, why wasn't 22:* paired up with 15:4 - it just paired with 20:5 to create a new tree. From initial obersvations it seems the tree does not need to be balanced or have any specific order other than that the frequencies of a leaf add up to the value of the parent node. Could two people creating a huffman tree with the same data end up with different encoding values?

  Read the article

• Huffman coding two characters as one

  - by Adomas

  Hi, I need huffman code(best in python or in java), which could encode text not by one character (a = 10, b = 11), but by two (ab = 11, ag = 10). Is it possible and if yes, where could i find it, maybe it's somewhere in the internet and i just can'd find it?

  Read the article

• What are the real-world applications of huffman coding?

  - by jcyang

  I am told that Huffman coding is used as loseless data compression algorithm but also am told that real data compress software do not employ huffman coding,cause if the keys are not distributed decentralized enough,the compressed file could be even larger than the orignal file. This leave me wondering are there any real-world application of huffman coding? thanks.

  Read the article

• Does it matter the direction of a Huffman's tree child node?

  - by Omega

  So, I'm on my quest about creating a Java implementation of Huffman's algorithm for compressing/decompressing files (as you might know, ever since Why create a Huffman tree per character instead of a Node?) for a school assignment. I now have a better understanding of how is this thing supposed to work. Wikipedia has a great-looking algorithm here that seemed to make my life way easier. Taken from http://en.wikipedia.org/wiki/Huffman_coding: Create a leaf node for each symbol and add it to the priority queue. While there is more than one node in the queue: Remove the two nodes of highest priority (lowest probability) from the queue Create a new internal node with these two nodes as children and with probability equal to the sum of the two nodes' probabilities. Add the new node to the queue. The remaining node is the root node and the tree is complete. It looks simple and great. However, it left me wondering: when I "merge" two nodes (make them children of a new internal node), does it even matter what direction (left or right) will each node be afterwards? I still don't fully understand Huffman coding, and I'm not very sure if there is a criteria used to tell whether a node should go to the right or to the left. I assumed that, perhaps the highest-frequency node would go to the right, but I've seen some Huffman trees in the web that don't seem to follow such criteria. For instance, Wikipedia's example image http://upload.wikimedia.org/wikipedia/commons/thumb/8/82/Huffman_tree_2.svg/625px-Huffman_tree_2.svg.png seems to put the highest ones to the right. But other images like this one http://thalia.spec.gmu.edu/~pparis/classes/notes_101/img25.gif has them all to the left. However, they're never mixed up in the same image (some to the right and others to the left). So, does it matter? Why?

  Read the article

• How should I compress a file with multiple bytes that are the same with Huffman coding?

  - by Omega

  On my great quest for compressing/decompressing files with a Java implementation of Huffman coding (http://en.wikipedia.org/wiki/Huffman_coding) for a school assignment, I am now at the point of building a list of prefix codes. Such codes are used when decompressing a file. Basically, the code is made of zeroes and ones, that are used to follow a path in a Huffman tree (left or right) for, ultimately, finding a byte. In this Wikipedia image, to reach the character m the prefix code would be 0111 The idea is that when you compress the file, you will basically convert all the bytes of the file into prefix codes instead (they tend to be smaller than 8 bits, so there's some gain). So every time the character m appears in a file (which in binary is actually 1101101), it will be replaced by 0111 (if we used the tree above). Therefore, 1101101110110111011011101101 becomes 0111011101110111 in the compressed file. I'm okay with that. But what if the following happens: In the file to be compressed there exists only one unique byte, say 1101101. There are 1000 of such byte. Technically, the prefix code of such byte would be... none, because there is no path to follow, right? I mean, there is only one unique byte anyway, so the tree has just one node. Therefore, if the prefix code is none, I would not be able to write the prefix code in the compressed file, because, well, there is nothing to write. Which brings this problem: how would I compress/decompress such file if it is impossible to write a prefix code when compressing? (using Huffman coding, due to the school assignment's rules) This tutorial seems to explain a bit better about prefix codes: http://www.cprogramming.com/tutorial/computersciencetheory/huffman.html but doesn't seem to address this issue either.

  Read the article

• Why create a Huffman tree per character instead of a Node?

  - by Omega

  For a school assignment we're supposed to make a Java implementation of a compressor/decompresser using Huffman's algorithm. I've been reading a bit about it, specially this C++ tutorial: http://www.cprogramming.com/tutorial/computersciencetheory/huffman.html In my program, I've been thinking about having Nodes that have the following properties: Total Frequency Character (if a leaf) Right child (if any) Left child (if any) Parent (if any) So when building the Huffman tree, it is just a matter of linking a node to others, etc. However, I'm a bit confused with the following quote (emphasis mine): First, every letter starts off as part of its own tree and the trees are ordered by the frequency of the letters in the original string. Then the two least-frequently used letters are combined into a single tree, and the frequency of that tree is set to be the combined frequency of the two trees that it links together. My question: why should I create a tree per letter, instead of just a node per letter and then do the linking later? I have not begun coding, I'm just studying the algorithm first, so I guess I'm missing an important detail. What is it?

  Read the article

• Deterministic and non uniform long string generation from seed

  - by Limonup

  I had this weird idea for an encryption that I wanted to try out, it may be bad, and it may have done before, but I'm just doing it for fun. The short version of the question is: Is it possible to generate a long, deterministic and non-uniformly distributed string/sequence of numbers from a small seed? Long(er) version: I was thinking to encrypt a text by changing encoding. The new encoding would be generated via Huffman algorithm. To work well, the Huffman algorithm would need a fairly long text with non uniform distribution. Then characters can have different bit-lengths which would be the primary strength of this encryption. The problem is that its impractical to enter in/remember a long text each time you want to decrypt the text. So I was wondering if it was possible to generate a text from password seed? It doesn't matter what the text is, as long as it has non uniform distribution of characters and that the exact same sequence can be recreated each time you give it the same seed. Preferably, are there any functions/extensions in Python that can do this? EDIT: To expand on the "strength" of varying bit length: if I have a string "test", ASCII values 116, 101, 115, 116, which gives bit values of 1110100 1100101 1110011 1110100 Then, say my Huffman algorithm generates encoding like t = 101 e = 1100111 s = 10001 The final string is 101 1100111 10001 101, if we encode this back to ASCII, we get 1011100 1111000 1101000, which is 3 entirely different characters. Obviously its impossible to perform any kind of frequency analysis or something like that on this.

  Read the article

• How to discriminate from two nodes with identical frequencies in a Huffman's tree?

  - by Omega

  Still on my quest to compress/decompress files with a Java implementation of Huffman's coding (http://en.wikipedia.org/wiki/Huffman_coding) for a school assignment. From the Wikipedia page, I quote: Create a leaf node for each symbol and add it to the priority queue. While there is more than one node in the queue: Remove the two nodes of highest priority (lowest probability) from the queue Create a new internal node with these two nodes as children and with probability equal to the sum of the two nodes' probabilities. Add the new node to the queue. The remaining node is the root node and the tree is complete. Now, emphasis: Remove the two nodes of highest priority (lowest probability) from the queue Create a new internal node with these two nodes as children and with probability equal to the sum of the two nodes' probabilities. So I have to take two nodes with the lowest frequency. What if there are multiple nodes with the same low frequency? How do I discriminate which one to use? The reason I ask this is because Wikipedia has this image: And I wanted to see if my Huffman's tree was the same. I created a file with the following content: aaaaeeee nnttmmiihhssfffouxprl And this was the result: Doesn't look so bad. But there clearly are some differences when multiple nodes have the same frequency. My questions are the following: What is Wikipedia's image doing to discriminate the nodes with the same frequency? Is my tree wrong? (Is Wikipedia's image method the one and only answer?) I guess there is one specific and strict way to do this, because for our school assignment, files that have been compressed by my program should be able to be decompressed by other classmate's programs - so there must be a "standard" or "unique" way to do it. But I'm a bit lost with that. My code is rather straightforward. It literally just follows Wikipedia's listed steps. The way my code extracts the two nodes with the lowest frequency from the queue is to iterate all nodes and if the current node has a lower frequency than any of the two "smallest" known nodes so far, then it replaces the highest one. Just like that.

  Read the article

• Compressibility Example

  - by user285726

  From my algorithms textbook: The annual county horse race is bringing in three thoroughbreds who have never competed against one another. Excited, you study their past 200 races and summarize these as prob- ability distributions over four outcomes: first (“first place”), second, third, and other. Outcome Aurora Whirlwind Phantasm 0.15 0.30 0.20 first 0.10 0.05 0.30 second 0.70 0.25 0.30 third 0.05 0.40 0.20 other Which horse is the most predictable? One quantitative approach to this question is to look at compressibility. Write down the history of each horse as a string of 200 values (first, second, third, other). The total number of bits needed to encode these track- record strings can then be computed using Huffman’s algorithm. This works out to 290 bits for Aurora, 380 for Whirlwind, and 420 for Phantasm (check it!). Aurora has the shortest encoding and is therefore in a strong sense the most predictable. How did they get 420 for Phantasm? I keep getting 400 bytes, as so: Combine first, other = 0.4, combine second, third = 0.6. End up with 2 bits encoding each position. Is there something I've misunderstood about the Huffman encoding algorithm? Textbook available here: http://www.cs.berkeley.edu/~vazirani/algorithms.html (page 156).

  Read the article

• Java - Need help with binary/code string manipulation

  - by ShrimpCrackers

  For a project, I have to convert a binary string into (an array of) bytes and write it out to a file in binary. Say that I have a sentence converted into a code string using a huffman encoding. For example, if the sentence was: "hello" h = 00 e = 01, l = 10, o = 11 Then the string representation would be 0001101011. How would I convert that into a byte? <-- If that question doesn't make sense it's because I know little about bits/byte bitwise shifting and all that has to do with manipulating 1's and 0's.

  Read the article

• C++ Structure within itself?

  - by Douglas

  I've been trying to port this code to python, but there is something I do not quite understand in C++ (I do know a bit of C++ but this is beyond me): typedef struct huffnode_s { struct huffnode_s *zero; struct huffnode_s *one; unsigned char val; float freq; } huffnode_t; What I don't get is how huffnode_s can be within itself, I've never seen this before and don't quite understand it. What does this mean, and if someone can, what would be the python equivalent?

  Read the article

• Webcam error (libv4lconvert) while capturing VIDEO

  - by shadyabhi

  I get the following when I capture images using my web-cam.. libv4lconvert: Error decompressing JPEG: unknown huffman code: 0000ffff libv4lconvert: Error decompressing JPEG: unknown huffman code: 0000ffff libv4lconvert: Error decompressing JPEG: unknown huffman code: 0000ffff ...(same error repeating) ... I also had issue that my camera was not getting detected in ubuntu. So, in order to run an application that uses the webcam, I have to run a command like LD_PRELOAD=/usr/lib/libv4l/v4l1compat.so ./6dofhand Whats causing these errors?

  Read the article

• Imagemagick PDF to JPG conversion failing

  - by Scott

  I'm trying to convert the first page of a PDF to a JPG. I'm pretty sure I got this to work with certain PDFs, but is it really possible that certain PDFs are made incorrectly and cannot be converted? I tried running this first: $ convert 10-03-26.pdf[1] test.jpg And I got the follow: Error: /syntaxerror in readxref Operand stack: Execution stack: %interp_exit .runexec2 --nostringval-- --nostringval-- --nostringval-- 2 %stopped_push --nostringval-- --nostringval-- --nostringval-- false 1 %stopped_push 1 3 %oparray_pop 1 3 %oparray_pop --nostringval-- --nostringval-- --nostringval-- --nostringval-- --nostringval-- --nostringval-- Dictionary stack: --dict:1062/1417(ro)(G)-- --dict:0/20(G)-- --dict:73/200(L)-- --dict:73/200(L)-- --dict:97/127(ro)(G)-- --dict:229/230(ro)(G)-- --dict:14/15(L)-- Current allocation mode is local ESP Ghostscript 7.07.1: Unrecoverable error, exit code 1 convert: Postscript delegate failed `10-03-26.pdf'. Running this instead: $ convert -verbose -colorspace rgb '10-03-26.pdf[1]' test.jpg I get the following: Error: /syntaxerror in readxref Operand stack: Execution stack: %interp_exit .runexec2 --nostringval-- --nostringval-- --nostringval-- 2 %stopped_push --nostringval-- --nostringval-- --nostringval-- false 1 %stopped_push 1 3 %oparray_pop 1 3 %oparray_pop --nostringval-- --nostringval-- --nostringval-- --nostringval-- --nostringval-- --nostringval-- Dictionary stack: --dict:1062/1417(ro)(G)-- --dict:0/20(G)-- --dict:73/200(L)-- --dict:73/200(L)-- --dict:97/127(ro)(G)-- --dict:229/230(ro)(G)-- --dict:14/15(L)-- Current allocation mode is local ESP Ghostscript 7.07.1: Unrecoverable error, exit code 1 "gs" -q -dBATCH -dSAFER -dMaxBitmap=500000000 -dNOPAUSE -dAlignToPixels=0 "-sDEVICE=pnmraw" -dTextAlphaBits=4 -dGraphicsAlphaBits=4 "-g792x1611" "-r72x72" -dFirstPage=2 -dLastPage=2 "-sOutputFile=/tmp/magick-XXU3T44P" "-f/tmp/magick-XXoMKL8Z" "-f/tmp/magic2eec1F"Start of Image Define Huffman Table 0x00 0 1 5 1 1 1 1 1 1 0 0 0 0 0 0 0 Define Huffman Table 0x01 0 3 1 1 1 1 1 1 1 1 1 0 0 0 0 0 Define Huffman Table 0x10 0 2 1 3 3 2 4 3 5 5 4 4 0 0 1 125 Define Huffman Table 0x11 0 2 1 2 4 4 3 4 7 5 4 4 0 1 2 119 End Of Image convert: Postscript delegate failed `10-03-26.pdf'. Why would the conversion fail? Just as an aside, this is happening on a (gs) Grid-Service on (mt) Media Temple hosting. I cannot install programs on the server, but both Imagemagick and Ghostscript are installed Thanks!

  Read the article

• wxCam can't open /dev/dsp

  - by SIJAR

  I try to run wxCam through PulseAudio using the following command: $ padsp -d wxcam Although wxCam started ok, wxCam is been set to use xdiv format to enable sound during recording, but while recording the I get the error: Cannot open /dev/dsp. Video file will be recorded without audio track Please help me in fixing this issue. Below is some debug information: $ padsp -d wxcam Determining video4linux API version... Using video4linux 2 API VIDIOC_ENUM_FRAMESIZES: Invalid argument V4L2_CID_GAMMA is not supported Determining pixel format... pixel format: YUV 4:2:2 (YUYV) Found V4L2_PIX_FMT_YUYV pixel format pixel format: MJPEG Found V4L2_PIX_FMT_MJPEG pixel format --DEBUG: [wxcam] Generating standard Huffman tables for this frame. Corrupt JPEG data: 2 extraneous bytes before marker 0xd2 ... repeats a couple of times ... open of failed: No such file or directory --DEBUG: [wxcam] Generating standard Huffman tables for this frame. Corrupt JPEG data: 2 extraneous bytes before marker 0xd4 ... repeats a couple of times .... /home/sij/Videos/Webcam/video.avi written: 640x480, 1334396 bytes --DEBUG: [wxcam] Generating standard Huffman tables for this frame. Corrupt JPEG data: 2 extraneous bytes before marker 0xd3 ... repeats a couple of times ...

  Read the article

• Imagemagick PDF to JPG conversion failing

  - by sbressler

  I'm trying to convert the first page of a PDF to a JPG. I'm pretty sure I got this to work with certain PDFs, but is it really possible that certain PDFs are made incorrectly and cannot be converted? I tried running this first: $ convert 10-03-26.pdf[1] test.jpg And I got the follow: Error: /syntaxerror in readxref Operand stack: Execution stack: %interp_exit .runexec2 --nostringval-- --nostringval-- --nostringval-- 2 %stopped_push --nostringval-- --nostringval-- --nostringval-- false 1 %stopped_push 1 3 %oparray_pop 1 3 %oparray_pop --nostringval-- --nostringval-- --nostringval-- --nostringval-- --nostringval-- --nostringval-- Dictionary stack: --dict:1062/1417(ro)(G)-- --dict:0/20(G)-- --dict:73/200(L)-- --dict:73/200(L)-- --dict:97/127(ro)(G)-- --dict:229/230(ro)(G)-- --dict:14/15(L)-- Current allocation mode is local ESP Ghostscript 7.07.1: Unrecoverable error, exit code 1 convert: Postscript delegate failed `10-03-26.pdf'. Running this instead: $ convert -verbose -colorspace rgb '10-03-26.pdf[1]' test.jpg I get the following: Error: /syntaxerror in readxref Operand stack: Execution stack: %interp_exit .runexec2 --nostringval-- --nostringval-- --nostringval-- 2 %stopped_push --nostringval-- --nostringval-- --nostringval-- false 1 %stopped_push 1 3 %oparray_pop 1 3 %oparray_pop --nostringval-- --nostringval-- --nostringval-- --nostringval-- --nostringval-- --nostringval-- Dictionary stack: --dict:1062/1417(ro)(G)-- --dict:0/20(G)-- --dict:73/200(L)-- --dict:73/200(L)-- --dict:97/127(ro)(G)-- --dict:229/230(ro)(G)-- --dict:14/15(L)-- Current allocation mode is local ESP Ghostscript 7.07.1: Unrecoverable error, exit code 1 "gs" -q -dBATCH -dSAFER -dMaxBitmap=500000000 -dNOPAUSE -dAlignToPixels=0 "-sDEVICE=pnmraw" -dTextAlphaBits=4 -dGraphicsAlphaBits=4 "-g792x1611" "-r72x72" -dFirstPage=2 -dLastPage=2 "-sOutputFile=/tmp/magick-XXU3T44P" "-f/tmp/magick-XXoMKL8Z" "-f/tmp/magic2eec1F"Start of Image Define Huffman Table 0x00 0 1 5 1 1 1 1 1 1 0 0 0 0 0 0 0 Define Huffman Table 0x01 0 3 1 1 1 1 1 1 1 1 1 0 0 0 0 0 Define Huffman Table 0x10 0 2 1 3 3 2 4 3 5 5 4 4 0 0 1 125 Define Huffman Table 0x11 0 2 1 2 4 4 3 4 7 5 4 4 0 1 2 119 End Of Image convert: Postscript delegate failed `10-03-26.pdf'. Why would the conversion fail? Thanks!

  Read the article

• Why am I unable to telnet to a local port that has a listening service?

  - by Skip Huffman

  I suspect this is either a very simple question, or a very complex one. I have a headless server running ubuntu 10.04 that I can ssh into. I have full root access to the system. I am trying to set up an ssh tunnel to allow me to vnc to the system (but that isn't my question. I have vnc running on port 5903, here is the netstat output for that: Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name tcp 0 0 0.0.0.0:5903 0.0.0.0:* LISTEN 7173/Xtightvnc tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 465/sshd But when I try to telnet to that port, from within the same system and login, I get unable to connect errors # telnet localhost 5903 Trying ::1... Trying 127.0.0.1... telnet: Unable to connect to remote host: Connection timed out I am able to telnet to port 22 (as a verification) ~# telnet localhost 22 Trying ::1... Connected to localhost. Escape character is '^]'. SSH-2.0-OpenSSH_5.3p1 Debian-3ubuntu7 I have tried to open up any possible ports using ufw (probably clumsy fashion) # ufw status numbered Status: active To Action From -- ------ ---- [ 1] 5903 ALLOW IN Anywhere [ 2] 22 ALLOW IN Anywhere What else might be blocking this connection locally? Thank you, Edit: The only reference to port 5903 in iptable -L -n is this: Chain ufw-user-input (1 references) target prot opt source destination ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:5903 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:5903 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:22 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:22 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:8080 ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:8080 I can post the whole output if that will be useful. hosts.allow and hosts.deny both contain only comments. Re-Edit: Some other questions pointed me to nmap, so I ran a portscan through that utility: # nmap -v -sT localhost -p1-65535 Starting Nmap 5.00 ( http://nmap.org ) at 2011-11-09 09:58 PST NSE: Loaded 0 scripts for scanning. Warning: Hostname localhost resolves to 2 IPs. Using 127.0.0.1. Initiating Connect Scan at 09:58 Scanning localhost (127.0.0.1) [65535 ports] Discovered open port 22/tcp on 127.0.0.1 Connect Scan Timing: About 18.56% done; ETC: 10:01 (0:02:16 remaining) Connect Scan Timing: About 44.35% done; ETC: 10:00 (0:01:17 remaining) Completed Connect Scan at 10:00, 112.36s elapsed (65535 total ports) Host localhost (127.0.0.1) is up (0.00s latency). Interesting ports on localhost (127.0.0.1): Not shown: 65533 filtered ports PORT STATE SERVICE 22/tcp open ssh 80/tcp closed http Read data files from: /usr/share/nmap Nmap done: 1 IP address (1 host up) scanned in 112.43 seconds Raw packets sent: 0 (0B) | Rcvd: 0 (0B) I think this shows that 5903 is blocked somehow. Which I pretty much knew. The question remains what is blocking it and how to modify. Re-re-edit: To check Paul Lathrop's suggested answer, I first verified my ip address with ifconfig: eth0 Link encap:Ethernet HWaddr 02:16:3e:42:28:8f inet addr:10.0.10.3 Bcast:10.0.10.255 Mask:255.255.255.0 Then tried to telnet to 5903 from that address: # telnet 10.0.10.3 5903 Trying 10.0.10.3... telnet: Unable to connect to remote host: Connection timed out No luck. Re-re-re-re-edit: Ok, I think I have isolated it a bit to vncserver, not the firewall, darn it. I shut off vncserver and had netcat listen on port 5903. My vnc client then was able to establish a connnection and sit and wait for a response. Looks like I should be chasing a vnc problem. At least that is progress Thanks for the help

  Read the article

• Python Bitstream implementations

  - by Danielb

  I am writing a huffman implementation in Python as a learning exercise. I have got to the point of writing out my variable length huffman codes to a buffer (or file). Only to find there does not seem to be a bitstream class implemented by Python! I have had a look at the array and struct modules but they do not seem to do what I need without extra work. A bit of goggling turned up this bitstream implementation, which is more like what I am wanting. Is there really no comparable bitstream class in the Python standard library?

  Read the article

• First look at the cloud with Google App Engine and Udacity

  - by Ken Hortsch

  Udacity is free online university and offers a CS253 intro to web development class.  Since I am currently a web developer/architect in ASP.Net (and recent project has brought me back to Java) it is a bit light.  However, it does offer me a nice problem set and my first exposure to writing cloud apps with GAE and Google Datastore. Steve Huffman, who developed reddit, is the instructor and does offer nice real-life stories.  Give it a look.

  Read the article

• Convert old AVI files to a modern format

  - by iWerner

  Hi, we have a collection of old home videos that were saved in AVI format a long time ago. I want to convert these files to a more modern format because the Totem Movie Player that comes with Ubuntu 10.4 seems to be the only program capable of playing them. The files seem to be encoded with a MJPEG codec, and playing them in VLC or Windows Media Player plays only the sound but there is no video. Avidemux was able to open the files, but the quality of the video is severely degraded: The video skips frames and is interlaced (it's not interlaced when playing it in Totem). Neither ffmpeg nor mencoder seems to be able to read the video stream. mencoder reports that it is using ffmpeg's codec. Here's a section from its output: ========================================================================== Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family [mjpeg @ 0x92a7260]mjpeg: using external huffman table [mjpeg @ 0x92a7260]mjpeg: error using external huffman table, switching back to internal Unsupported PixelFormat -1 Selected video codec: [ffmjpeg] vfm: ffmpeg (FFmpeg MJPEG) while running ffmpeg produces the following: $ ffmpeg -i input.avi output.avi FFmpeg version SVN-r0.5.1-4:0.5.1-1ubuntu1, Copyright (c) 2000-2009 Fabrice Bellard, et al. configuration: --extra-version=4:0.5.1-1ubuntu1 --prefix=/usr --enable-avfilter --enable-avfilter-lavf --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --disable-stripping --disable-vhook --enable-runtime-cpudetect --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --enable-shared --disable-static libavutil 49.15. 0 / 49.15. 0 libavcodec 52.20. 1 / 52.20. 1 libavformat 52.31. 0 / 52.31. 0 libavdevice 52. 1. 0 / 52. 1. 0 libavfilter 0. 4. 0 / 0. 4. 0 libswscale 0. 7. 1 / 0. 7. 1 libpostproc 51. 2. 0 / 51. 2. 0 built on Mar 4 2010 12:35:30, gcc: 4.4.3 [avi @ 0x87952c0]non-interleaved AVI Input #0, avi, from 'input.avi': Duration: 00:00:15.24, start: 0.000000, bitrate: 22447 kb/s Stream #0.0: Video: mjpeg, yuvj422p, 720x544, 25 tbr, 25 tbn, 25 tbc Stream #0.1: Audio: pcm_s16le, 44100 Hz, stereo, s16, 1411 kb/s Output #0, avi, to 'output.avi': Stream #0.0: Video: mpeg4, yuv420p, 720x544, q=2-31, 200 kb/s, 90k tbn, 25 tbc Stream #0.1: Audio: mp2, 44100 Hz, stereo, s16, 64 kb/s Stream mapping: Stream #0.0 -> #0.0 Stream #0.1 -> #0.1 Press [q] to stop encoding frame= 0 fps= 0 q=0.0 Lsize= 143kB time=15.23 bitrate= 76.9kbits/s video:0kB audio:119kB global headers:0kB muxing overhead 20.101777% So the problem is that output does not contain any video, as evidenced by the video:0kB at the end. In all of the above cases the audio comes out fine. So my question is: What can I do to convert these files to a more modern format with more modern codecs?

  Read the article

• GDC 2012: DXT is NOT ENOUGH! Advanced texture compression for games

  GDC 2012: DXT is NOT ENOUGH! Advanced texture compression for games (Pre-recorded GDC content) Tired of fighting to fit your textures on disk? Too many bad reviews on long download times? Fix it! Don't settle for putting your raw DXT files in a ZIP, instead, compress your DXT textures by an extra 50%-70%! This talk will cover various ways to increase the compression of your game textures to allow for smaller distributables without introducing error, and allowing for fast on-demand decompression at run time. We'll cover how to losslessly squeeze your data with Huffman, block expansion, vector quantization, and we'll even take a look at what MegaTexture is doing too. If you've ever fought to fit textures into memory, this is the talk for you. Speaker: Colt McAnlis From: GoogleDevelopers Views: 1132 21 ratings Time: 33:05 More in Science & Technology

  Read the article

• Udacity: Teaching thousands of students to program online using App Engine

  Udacity: Teaching thousands of students to program online using App Engine Join Fred Sauer & Iein Valdez as they talk with Steve Huffman, founder of Reddit and Hipmunk, and Chris Chew, senior software engineer at Udacity. Steve will share his experience teaching a course on web development using App Engine at Udacity, and Chris will talk about his experience building Udacity itself using App Engine. Submit your questions for Steve and Chris to answer live on air. From: GoogleDevelopers Views: 0 0 ratings Time: 00:00 More in Science & Technology

  Read the article

• Simple/efficient text compression

  - by arthurprs

  What's the simplest, but efficient compression algorithm? Deflate, lzma, etc. aren't valid options. I need something that compiles really small, like: RLE, LZX, Huffman, etc.. Note: The data is 95% ASCII text

  Read the article

• writing 'bits' to c++ file streams

  - by Sorush Rabiee

  How can i write 'one bit' into a file stream or file structure each time? is it possible to write to a queue and then flush it ? is it possible with c# or java? this was needed when i try to implement an instance of Huffman codding. i can't write bits into files. so write them to a bitset and then (when compression was completed) write 8-bit piece of it each time (exclude last one).

  Read the article

• Use ImageMagick to convert TIFF to PNGs, how to improve the speed?

  - by Woo

  I am using "convert" from IM to get PNGs from multi-page TIFF files, everything is good except the speed. From "convert" documentation, I found: For the MNG and PNG image formats, the quality value sets the zlib compression level (quality / 10) and filter-type (quality % 10). For compression level 0, the Huffman-only strategy is used, which is fastest but not necessarily the worst compression. The default PNG compression is 75. So I tried "-quality 0", but almost no changes with the spreed. Anyone can share the ideas of how to improve the spreed? Here are my command: convert 100Pages.tif[0,1,2,3,4,5] -quality 0 100Pages.png Thanks!

  Read the article

• I need to choose a compression algorithm

  - by chiz

  I need to choose a compression algorithm to compress some data. I don't know the type of data I'll be compressing in advance (think of it as kinda like the WinRAR program). I've heard of the following algorithms but I don't know which one I should use. Can anyone post a short list of pros and cons? For my application the first priority is decompression speed; the second priority is space saved. Compression (not decompression) speed is irrelevant. Deflate Implode Plain Huffman bzip2 lzma

  Read the article

1 2  | Next Page >