Skip to main content

Refreshing Android MediaStore

The Android MediaStore maintains the metadata of audio, video and image files in the underlying filesystem for convenient consumption by relevant Android apps (eg. music player).

The problem is when manipulating the SD card content with an Android file manager, sometimes the metadata cache becomes out of sync with the actual filesystem. So for example if you rename or delete a folder using a file manager, then connect the device via a USB cable to your PC to be accessed via MTP, the old folder may appear in Windows Explorer. Clicking "Refresh" does not work to update the content. The only way to refresh the cache is to reboot the device.

Another method I found recently is to run an app that forces MediaStore to refresh its cache. There are many apps available for this purpose if you search for "rescan sd" in the app store. A lot of them won't work with Android 6.x (Mashmallow) and will crash when you try. One ad-free app that works  under Mashmallow is Rescan SD Card.



It is a very simple app, but it does take a while to rescan the entire SD card. For my case with a few thousand files, it took 3 to 4 minutes to complete the process.

On the topic of MTP, it is a horrible protocol for file transfer. We used to have USB mass storage, where the SD card is mounted as a drive under Windows Explorer. But this is all but gone in the latest devices and can only be found in some custom ROMs.

Anyway, mounting the SD card as a drive has its own problems because it needs to dismount the storage from Android apps during the usage duration, which can cause all sorts of unexpected problems. Recent devices mostly only support PTP (which is practically useless for anything) and MTP.

MTP is horrible because it is extremely finicky. It can hang when transferring large files. It can hang when you are just renaming a folder. When it hangs, the only workaround is to reboot the device.

Why not use wireless? Wireless transfer apps such as AirDroid or SendAnywhere is not practical when you are trying to transfer large files (eg. video files > 500MB). In addition, when you are out and about, and your PC is connected to a WiFi hotspot, while your phone is connected to 4G, it is a pain to juggle the connections so that the quota on your 4G broadband will not be affected. Simplest is to use a USB cable, which is fast and reliable. Too bad the underlying protocol is garbage.

We need a better standard for wired file transfer over USB, and so far none is forthcoming.

Comments

Popular posts from this blog

Update: Line adapter for Ozito Blade Trimmer

Update (Dec 2021): If you access to a 3D printer, I would now recommend this solution , which makes it super easy to replace the trimmer line. I have been using it for a few months now with zero issue.

Filament Joiner Part 2 (With Display and Knob)

Thanks to the current corona-virus crisis, the parts I ordered for the filament joiner project were taking forever to arrive. But now that they have finally arrived, I can put them to good use. These were the parts ordered: 0.96" OLED display SSD1306 Rotary switch encoder KY-040 Here is the final circuit diagram: The OLED display is connected to the SDA and SCL pins of the Nano (A4 and A5 respectively), and powered by 5V and GND. The rotary switch encoder is connected as follows: VCC => 5V GND = > GND CLK => D9 DT => D8 SW => D2 My prototype board now looks like this: The updated code for driving the knob and display is available in  heater-with-display.ino in the Github repository . We now have a fairly compact (about 7cm x 5cm) and independent filament joiner (no need to connect to PC) that is driven solely by a 12V power supply. Here's how to use it to join printer filaments. More usage details in my previous post .

Adding "Stereo Mixer" to Windows 7 with Conexant sound card

This procedure worked for my laptop (Thinkpad E530) with a Conexant 20671 sound card, but I suspect it will work for other sound cards in the Conexant family. I was playing with CamStudio to do a video capture of a Flash-based cartoon so that I can put it on the WDTV media player and play it on the big screen in the living room for my kids. The video capture worked brilliantly, but to do a sound capture, I needed to do some hacking. Apparently, there was this recording device called "Stereo Mixer" that was pretty standard in the Windows XP days. This allowed you to capture whatever was played to the speaker in all its digital glory. Then under pressure from various organizations on the dark side of the force, Microsoft and soundcard makers starting disabling this wonderful feature from Windows Vista onwards. So after much Googling around, I found out that for most sound cards, the hardware feature is still there, just not enabled on the software side. Unfortunately, to