HDCAM SR was introduced in 2003 and standardised in SMPTE 409M-2005. It uses a higher particle density tape and is capable of recording in 10 bits 4:2:2 or 4:4:4 RGB with a video bitrate of 440 Mbit/s, and a total data rate of approx. 600 Mbit/s. The increased bitrate (over HDCAM) allows HDCAM SR to capture much more of the full bandwidth of the HDSDI signal (19201080). Some HDCAM SR VTRs can also use a 2x mode with an even higher video bitrate of 880 Mbit/s, allowing for a single 4:4:4 stream at a lower compression or two 4:2:2 video streams simultaneously. HDCAM SR uses MPEG-4 Part 2 Simple Studio Profile for compression, and expands the number of audio channels up to 12 at 48 kHz/24-bit.