Video Quality
RTÉ Two HD is currently broadcasting at a high definition resolution of 1440x1088i. All other TV channels are broadcasting at standard definition resolution, 544x576i.
The content on RTÉ Two HD is mostly upscaled material. This means that the source is SD, but upscaled (or resized) to HD before broadcast. Upscaled HD is better quality than SD, but will be inferior to "full" HD.
Major sporting events (Rugby and Soccer internationals, certain GAA matches etc) are broadcast on RTÉ Two HD at full HD resolution.
The below screenshot shows "Life" in upscaled HD on RTÉ Two.
The below screenshots show RTÉ One in SD at 544x576i
Audio Quality
Both the TV and Radio channels use stereo MPEG-1 Audio Layer II (MP2), with 48kHz sample rate and a bit rate of 192Kbps which gives a good level of sound quality.