Xavier Robin – Tag – Phototag:xavier.robin.name,2010-05-28:/fr/feed/tag/photo2013-01-23T12:26:50.833773000+01:00weekly2https://xavier.robin.name/fr/img/favicon.icoXavier Robinhttps://xavier.robin.name/fr/contactTranscend class 10 vs. SanDisk Extreme Pro: a real-case scenariotag:xavier.robin.name,2012-12-28:/blog/2012/12/28/transcend-class-10-vs-sandisk-extreme-pro-a-real-case-scenario2012-12-28T18:34:33+01:002012-12-28T18:34:33+01:00<p>I own a Pentax K-5 with Transcend Class 10 cards (2 x 16 GB + 1 x 64 GB) and I am mostly satisfied with it. However I have been wondering if a better SD card (such as a SanDisk Extreme Pro 95 MB/s) would make a noticeable difference. I mean, it does on the paper in controlled tests. But is it really any better inside the camera? I mean, isn't the limiting factor the camera itself? So I just bought a 8 GB Extreme Pro one and tested the time necessary to write 10 pictures to the card in the camera and display the photo on the screen. This is a rather typical scenario: you shoot and wait to see the result. I also tested a slower SanDisk Class 4 card just for the fun.</p>
<h2>Test setup</h2>
<p>The Pentax K-5 was fixed on a tripod, aiming at a white paper sheet and manually focused. The mode was set to M, 80 ISO, 1/80s and F/2.8. The “all-manual” settings should eliminate most variations coming from refocusing or different exposure times. The drive mode was set to continuous shooting (Lo), taking about 1.5 image/second.</p>
<p>With each card, I repeat the following procedure 5 times. I put the card in the camera, turn it on, format the card, and press the trigger until 10 shots are taken. I then start the chronometer as soon as the last shot is taken (<a href="https://play.google.com/store/apps/details?id=com.remaxer.utility.chronometer">with the Android App Chronometer by REmaxer</a>), wait until the last image appears on the screen and stop the chronometer as soon as possible. The resulting images (DNG + JPG) for each shot are about 25 MB, summing up to a total of 250 MB for each test. I should note that the cards were put in the camera in more or less random order, and changed each time (so I didn't do all the test for a card in a row).</p>
<p>The following 5 cards were tested:</p>
<ul>
<li>SanDisk Extreme Pro 8GB Class 10 UHS-I</li>
<li>SanDisk Ultra 4GB Class 4</li>
<li>2 Transcend 16GB Class 10</li>
<li>Transcend 64GB Class 10</li>
</ul>
<h2>Results</h2>
<p class="imglegende"><img src="/files/blog/2012/12/28/Boxplots_edited_500.png"><span>Time to display the last photo after the last of 10 shots (in seconds). The lower the better.</span></p>
<p>Unsurprisingly, the class 4 card is the worst. I had to wait more than 13 seconds after the last shot before I could see anything displayed on the screen. It is more than 10 seconds more than with the best cards. Clearly not a good choice.</p>
<p>Next thing, and still quite unsurprising, the SanDisk Extreme Pro was the fastest card, with an average of 3 seconds between the last shot and its display on screen. This is slightly better than the Transcend Class 10 cards.</p>
<p>The real surprise came from the Transcend cards. First, the 64 GB was significantly slower than the 16 GB ones, with about 7 seconds required to display the last photo versus only 3.5 – 4. Probably the controller isn't able to cope with all this space to allocate? Second, the two 16 GB cards performed fairly differently, one being noticeably slower than the other. More precisely, it had a few “outlier” points where it would take up to 5 seconds to display the last shot. I repeated the test several more times and came to the same conclusion: only one of the card displayed this feature. All other cards had much more stable results.</p>
<h2>Conclusion</h2>
<p>So, are the more expensive cards really better?</p>
<p>Well, the first thing we can conclude is that cheap class 4 cards are clearly slower. At least the SanDisk Ultra. Since Transcend class 10 cards are about the same price but much, much faster (even in the worst-case outlier scenario), the latter should be prefered.</p>
<p>Then, is it worth buying a SanDisk ExtremePro that is 2.5–3 times more expensive (at the same capacity)? Well, it depends if the 0.5–1 second gain really means something to you. It may be significant on the field when the action is taking place <em>right now</em> and you quickly need to check your photos are OK before continuing.</p>
<p>Several questions remain.</p>
<ul>
<li>Is the bad Transcend 16 GB an exception or is it a frequent issue? Is it because it's already more than 1.5 years old (and used pretty intensively)?</li>
<li>Would I have different results if I tested a second Extreme Pro? And what about 16 GB ones?</li>
<li>If I had a 8 GB Transcend, would it be faster than the 16 GB ones (and thus could compete with the Extreme Pro)?</li>
<li>I bought the 64 GB card more than a year ago. Did Transcend improve their controller since?</li>
<li>How would a 64 GB Extreme Pro perform? Would it have the same controller issues than the Transcend?</li>
</ul>
<p>As you can see, my testings raise more questions than they solve. For now, I will keep the Extreme Pro in my K-5, with spare Transcends in the bag for when the 8 GB are full (with > 150 photos it shouldn't happen that often). I think this kind of setup is quite efficient: a small, fast card for everyday photos, and big, cheap ones available when more space is needed, at the cost of slightly slower shooting.</p>Convert Pentax K-5 AVI video to OGG for wikipedia in Ubuntu Precise Pangolin… with no clickstag:xavier.robin.name,2012-08-01:/blog/2012/08/01/convert-pentax-k-5-avi-video-to-ogg-for-wikipedia-in-ubuntu-precise-pangolin-with-no-clicks2012-08-01T16:34:22+02:002012-08-01T16:34:22+02:00<p>I captured a video with my Pentax K-5, and I wanted to send it to Wikipedia (in fact, to Wikimedia Commons) where OGG files are required. The conversion can be done very easily under Linux with avconv (previously known as ffmpeg):</p>
<pre>avconv -i IMGP7212.AVI -acodec libvorbis -ab 256k -ac 2 -vcodec libtheora -qscale 10 IMGP7212.ogg</pre>
<p>However, the sound is poor because there are <em>clicks</em> (or thumps or cracks or whatever you want) every second or so. Apparently it is <a href="http://www.pentaxforums.com/forums/pentax-k-5/131842-thump-sound-video.html">frequent issue</a> that is hardware or software dependent. I get a good sound if I play the video in VLC, apparently the PCM audio is correctly handled. As VLC can convert media files, I used it to get a video with a decent audio.</p>
<p>Let's go through.</p>
<ol>
<li>The first step is to open VLC and select the Media > “Convert / Save” menu. Select your file and click on the “Convert / Save” button.</li>
<li>Select the destination file.</li>
<li>In the Profile setting, choose “Video – Theora + Flac (OGG)”. You need vorbis audio encoding if you want the sound track to play in Firefox (and probably others), but on my computers the vorbis encoder is broken. We'll care about that later.</li>
<li>Click on the “Edit selected profile” button just on the right of the profile.</li>
<li>In the Video codec tab, make sure the Video checkbox is checked, “Keep original video track” is unchecked and Theora is selected as codec. Select a good bitrate (you can go up to 5000 or 10000 kb/s if you want a good quality and your video isn't too long. It'll generate a big video file, but not at all as big as the original AVI anyway, and Mediawiki will resize the video itself when it sends it to the web browsers.).</li>
<li>Select Frame Rate and Width according to the video options you have set in your K-5. Leave the Scale and Height fields blank (or 0)</li>
<li>In the Audio codec tab, make sure the Audio checkbox is checked, “Keep original audio track” is unchecked and the Flac codec is selected. I believe Bitrate is ignored. Channels is 1 but we will switch to 2 later anyway, so put what you want here. Sample Rate is 44100.</li>
<li>Click Save.</li>
<li>Click Start.</li>
<li>Wait.</li>
</ol>
<p>When the conversion is done in VLC, we switch to a command line to re-encode the audio track in vorbis. We set the vorbis codec (<code>-acodec libvorbis</code>), with a good bit rate (<code>-acodec libvorbis</code>) and 2 channels (<code>-ac 2</code>, apparently avconv cannot deal with only 1). We keep the video track intact (<code>-vcodec copy</code>).</p>
<pre>avconv -i IMGP2712.ogg -acodec libvorbis -ab 256k -ac 2 -vcodec copy IMGP2712_vorbis.ogg</pre>
<p>And that's it! You can now upload your video that doesn't click.</p>Genève en février…tag:xavier.robin.name,2011-02-27:/blog/2011/02/27/geneve-en-fevrier2011-02-27T17:51:05+01:002013-10-22T07:41:09+02:00<p>… c'est déjà le printemps !</p>
<h2>Les ronces, lauriers, lierres et houx sont toujours là</h2>
<p class="image"><a href="/files/fevrier/ronces.jpg"><img src="/files/fevrier/thumbs/ronces.jpg" alt="Ronces en sous-bois"></a><small>Ronces</small><br>
<a href="/files/fevrier/laurier.jpg"><img src="/files/fevrier/thumbs/laurier.jpg" alt="Laurier-cerise en sous-bois"></a><small>Laurier-cerise</small><br>
<a href="/files/fevrier/lierre.jpg"><img src="/files/fevrier/thumbs/lierre.jpg" alt="Lierre en sous-bois"></a><small>Lierre</small><br>
<a href="/files/fevrier/houx.jpg"><img src="/files/fevrier/thumbs/houx.jpg" alt="Houx en sous-bois"></a><small>Houx</small></p>
<h2>À l'intérieur, tout est fleuri</h2>
<p class="image"><a href="/files/fevrier/aechmea_fasciata.jpg"><img src="/files/fevrier/thumbs/aechmea_fasciata.jpg" alt="Aechmea fasciata" title="Aechmea fasciata"></a><small>Bromélie (Aechmea fasciata)</small><br>
<a href="/files/fevrier/clivia_miniata.jpg"><img src="/files/fevrier/thumbs/clivia_miniata.jpg" alt="Clivia miniata" title="Clivia miniata"></a><small>Clivia miniata</small><br>
<a href="/files/fevrier/phalenopsis.jpg"><img src="/files/fevrier/thumbs/phalenopsis.jpg" alt="Phalenopsis" title="Phalenopsis"></a><small>Phalenopsis</small></p>
<h2>Mais dehors aussi !</h2>
<p class="image"><a href="/files/fevrier/viorne.jpg"><img src="/files/fevrier/thumbs/viorne.jpg" alt="Viorne"></a><small>Viorne</small><br>
<a href="/files/fevrier/jasmin_d_hiver.jpg"><img src="/files/fevrier/thumbs/jasmin_d_hiver.jpg" alt="Jasmin d'hiver"></a><small>Jasmin d'hiver</small><br>
<a href="/files/fevrier/rose_de_noel.jpg"><img src="/files/fevrier/thumbs/rose_de_noel.jpg" alt="Rose de noël"></a><small>Rose de noël</small><br>
<a href="/files/fevrier/perce-neige.jpg"><img src="/files/fevrier/thumbs/perce-neige.jpg" alt="Perce-neige"></a><small>Perce-neige et</small><br>
<a href="/files/fevrier/primevere.jpg"><img src="/files/fevrier/thumbs/primevere.jpg" alt="Primevère"></a><small>Primevère évidemment</small><br></p>
<h2>Et ce n'est pas tout…</h2>
<p class="image"><a href="/files/fevrier/scilla.jpg"><img src="/files/fevrier/thumbs/scilla.jpg" alt="Scilla"></a><small>Scilla</small><br>
<a href="/files/fevrier/veronique.jpg"><img src="/files/fevrier/thumbs/veronique.jpg" alt="Véronique"></a><small>Véronique</small><br>
<a href="/files/fevrier/violette.jpg"><img src="/files/fevrier/thumbs/violette.jpg" alt="Violette"></a><small>Violette</small><br>
<a href="/files/fevrier/paquerette.jpg"><img src="/files/fevrier/thumbs/paquerette.jpg" alt="Pâquerettes"></a><small>Pâquerettes</small><br>
<a href="/files/fevrier/pissenlit.jpg"><img src="/files/fevrier/thumbs/pissenlit.jpg" alt="Pissenlit"></a><small>Pissenlit</small><br>
<a href="/files/fevrier/noisettier male.jpg"><img src="/files/fevrier/thumbs/noisettier male.jpg" alt="noisettier male"></a>
<a href="/files/fevrier/noisettier_femelle.jpg"><img src="/files/fevrier/thumbs/noisettier_femelle.jpg" alt="noisettier femelle"></a><small>Noisettier mâle et femelle</small><br>
<a href="/files/fevrier/lamier.jpg"><img src="/files/fevrier/thumbs/lamier.jpg" alt="Lamier"></a><small>Lamier</small><br>
<a href="/files/fevrier/hellebore.jpg"><img src="/files/fevrier/thumbs/hellebore.jpg" alt="Hellebore"></a><small>Hellebore</small><br>
<a href="/files/fevrier/fausse_arabette.jpg"><img src="/files/fevrier/thumbs/fausse_arabette.jpg" alt="Fausse arabette"></a><small>Fausse arabette</small><br>
<a href="/files/fevrier/cyclamen.jpg"><img src="/files/fevrier/thumbs/cyclamen.jpg" alt="Cyclamen"></a><small>Cyclamen</small><br>
<a href="/files/fevrier/corydale rose.jpg"><img src="/files/fevrier/thumbs/corydale rose.jpg" alt="Scilla"></a>
<a href="/files/fevrier/corydale_blanche.jpg"><img src="/files/fevrier/thumbs/corydale_blanche.jpg" alt="corydale blanche"></a><small>Corydale rose et blanche</small><br>
<a href="/files/fevrier/buis.jpg"><img src="/files/fevrier/thumbs/buis.jpg" alt="Buis"></a><small>Buis</small><br>
<a href="/files/fevrier/arbuste.jpg"><img src="/files/fevrier/thumbs/arbuste.jpg" alt="Arbuste à petites fleurs jaunes"></a><small>et même un arbuste non identifé sont en fleurs.</small></p>
<h2>Les insectes aussi sont sortis</h2>
<p class="image"><a href="/files/fevrier/abeille.jpg"><img src="/files/fevrier/thumbs/abeille.jpg" alt="abeille"></a><small>abeille</small><br>
<a href="/files/fevrier/bourdon_dans_un_crocus.jpg"><img src="/files/fevrier/thumbs/bourdon_dans_un_crocus.jpg" alt="Bourdon dans un crocus jaune"></a><small>bourdon (dans un crocus)</small><br>
<a href="/files/fevrier/gendarme.jpg"><img src="/files/fevrier/thumbs/gendarme.jpg" alt="Gendarmes"></a><small>gendarmes et</small><br>
<a href="/files/fevrier/papillon.jpg"><img src="/files/fevrier/thumbs/papillon.jpg" alt="Papillon"></a><small>même un papillon</small></p>
<h2>Ce n'est pas fini, d'autres vont suivres</h2>
<p class="image"><a href="/files/fevrier/arum.jpg"><img src="/files/fevrier/thumbs/arum.jpg" alt="Arum"></a><small>arum</small><br>
<a href="/files/fevrier/forythia.jpg"><img src="/files/fevrier/thumbs/forythia.jpg" alt="Forythia"></a><small>forythia</small><br>
<a href="/files/fevrier/jonquille.jpg"><img src="/files/fevrier/thumbs/jonquille.jpg" alt="Jonquille"></a><small>jonquille</small><br>
<a href="/files/fevrier/mahonia.jpg"><img src="/files/fevrier/thumbs/mahonia.jpg" alt="Mahonia"></a><small>mahonia</small><br>
<a href="/files/fevrier/viorne2.jpg"><img src="/files/fevrier/thumbs/viorne2.jpg" alt="Viorne"></a><small>viorne</small><br>
<a href="/files/fevrier/phalangere_ou_autre.jpg"><img src="/files/fevrier/thumbs/phalangere_ou_autre.jpg" alt="Phalangère ou autre"></a><small>probablement une phalangère</small><br>
<a href="/files/fevrier/phalangere_perce-feuille_morte.jpg"><img src="/files/fevrier/thumbs/phalangere_perce-feuille_morte.jpg" alt="Phalangère perçant une feuille morte"></a><small>et même une qui perce une feuille morte !</small></p>
<h2>Pas de doute, le printemps est déjà bien parti</h2>
<p>Mais les nuages revienne déjà… la pluie est pour bientôt.</p>
<p class="image"><a href="/files/fevrier/nuages.jpg"><img src="/files/fevrier/thumbs/nuages.jpg" alt="Nuages"></a></p>