A media processing comparison system (“MPCS”) and techniques facilitate concurrent, subjective quality comparisons between media presentations produced by different instances of media processing components performing the same functions (for example, instances of media processing components in the form of hardware, software, and/or firmware, such as parsers, codecs, decryptors, and/or demultiplexers, supplied by the same or different entities) in a particular media content player. The MPCS receives an ordered stream of encoded media samples from a media source, and decodes a particular encoded media sample using two or more different instances of media processing components. A single renderer renders and/or coordinates the synchronous presentation of decoded media samples from each instance of media processing component(s) as separate media presentations. The media presentations may be subjectively compared and/or selected for storage by a user in a sample-by-sample manner.