Launched within the early 2000’s, HitClips was a digital audio participant ecosystem that relied on cartridges containing a mere 60 seconds of music, therefore the identify. So after discovering a DIY challenge that aimed to permit customers to play a number of hours of music with an unique HitClips participant and microSD card, Alex from the YouTube channel Tremendous Make One thing was impressed to make a transportable video participant. Much like the beforehand talked about HitClips mod, his system would retailer movies on an SD card for later playback and incorporate the far-cheaper ESP32, somewhat than utilizing a fancy Raspberry Pi-based resolution.
Two of the principle objectives concerning this challenge have been to permit for almost anybody to construct it with out the necessity for superior soldering abilities and/or tools, and include modular elements for simple modifications. Three configurations have been deliberate, together with video solely, video and audio, and one which provides a big battery to the again for final portability. All of those designs have been additionally based mostly off of a single PCB and almost equivalent elements.
As said earlier than, this method makes use of an ESP32 to decode video recordsdata and play them. To make issues simpler to solder, Alex went with the favored ESP-WROOM-32 growth equipment that already incorporates a USB-to-serial conversion IC for simple programming. Audio is produced from both the onboard 8 ohm speaker or the three.5mm headphone jack, each of that are powered by a single PAM8403 audio amplifier module that receives its alerts from the ESP32’s built-in DAC. Final of all and most significantly, movies are seen on a 1.8″ ST7735 LCD with a decision of 160×128 pixels. Inputs are learn from a pair of potentiometers on the base or the 2 momentary pushbuttons on the facet.
Practically all trendy video codecs depend on superior codecs equivalent to H.264/265 or AV-1 since they scale back the file dimension whereas concurrently sustaining many of the picture high quality. Though these are nice for streaming, their want for ample processing means lower-powered gadgets are unable to fulfill the required framerate. To get round this, Alex opted to make use of the MJPEG codec as a substitute. It really works by compressing every body of the video right into a single, lossy JPEG picture, which is then stitched along with all the different compressed frames to make the video. Though the file dimension is bigger in comparison with H.264 on the identical bit-rate, its decrease necessities for decoding makes it excellent on this software.
Alex started by laying out every part in an Altium Designer schematic and connecting them along with digital ‘nets’. From right here, he laid them out inside the boundary of an appropriately-sized cell participant and routed the traces. As soon as Alex acquired the fabricated boards, he assembled them by hand utilizing a particular approach for connecting the through-holes of the ESP32 growth equipment to the SMD pads resulting from its lack of castellated edges.
To check this creation, Alex used FFMPEG to rapidly convert a video file from the mixed MP4 format into separate MP3 and MJPEG recordsdata for playback on the ESP32. As soon as booted, the mini video participant labored precisely as meant, as he might each see and listen to the media recordsdata saved on the SD card. For extra info, you may watch Alex’s video right here on YouTube.