The MPEG standard was defined by the Motion Picture Experts Group and later, compliant formats were developed including .mpg, .mpeg, .m1v, .mp2, .mp3, .mpa, .mpe, .mpv2 and .m3u. These formats are still an evolving set of specifications for audio and video compression. The MPEG standard allows to encode progressive video at a transmission rate of about 1.5 million bps (bits per second). The .mpeg format was designed specifically for use with Video-CD and CD-i media. The most common implementation of the MPEG-1 standard allows video resolution of 352x240 at 30 fps (frames per second). MPEG video files usually suffer a slight loss of quality compared to typical VCR videos.