Difference between revisions of "Bit Rate Calculation"
(56 intermediate revisions by 2 users not shown) | |||
Line 33: | Line 33: | ||
The values of Audio Data for audio format, sampling frequency and quality (MP3 bitrate average), come from Instreamer Manual (firmware V3.10 – page 18 - [http://www.barix.com/downloads/ | The values of Audio Data for audio format, sampling frequency and quality (MP3 bitrate average), come from Instreamer Manual (firmware V3.10 – page 18 - [http://www.barix.com/downloads/Instreamer_Standard_Firmware/1981/]) | ||
For MPEG1/2 Layer3 (MP3) bit rate | |||
the following Encoding range is supported as Constant & Variable Bit Rate in IPAM102 based devices (e.g. new Instreamer): | |||
28kbps (MPEG2@16KHz mono) - 320kbps (MPEG1@48KHz stereo)<br> | |||
the following Encoding range is supported as Variable Bit Rate in IPAM100 based devices (e.g. old Instreamer100): | |||
28kbps (MPEG2@16KHz mono) - 192kbps (MPEG1@48KHz stereo)<br> | |||
Decoding range on both IPAM100 and IPAM300 as Constant or Variable Bit Rate is: | |||
8kbps (MPEG2) - 320kbps (MPEG1) | |||
Line 40: | Line 57: | ||
'''Total Bit Rate (Kbit/sec) = Audio Data Rate (Kbit/sec) + Overhead/sec (Kbit/sec)''' | '''Total Bit Rate (Kbit/sec) = Audio Data Rate (Kbit/sec) + Overhead/sec (Kbit/sec)''' | ||
(Kbit = 1000 bit) | <sup>''(1 Kbit = 1000 bit)''</sup> | ||
{| class="wikitable" border="1" cellspacing="0" | {| class="wikitable" border="1" cellspacing="0" | ||
| <center>'''Audio Format'''</center> | | <center>'''Audio Format (MP3 in VBR)'''</center> | ||
| <center>'''Audio Data Rate (Kbit/sec)'''</center> | | <center>'''Audio Data Rate (Kbit/sec)'''</center> | ||
| <center>'''Packet/sec (Wireshark)'''</center> | | <center>'''Packet/sec (Wireshark)'''</center> | ||
Line 167: | Line 183: | ||
'''Without Ethernet Overhead''' | '''Without Ethernet Overhead''' | ||
{| class=" | {| class="wikitable" border="1" cellspacing="0" | ||
| <center>'''Audio Format'''</center> | | <center>'''Audio Format (MP3 in VBR)'''</center> | ||
| <center>'''Audio Data Rate | | <center>'''Audio Data Rate (Kbit/sec)'''</center> | ||
| <center>'''Packet/sec (Wireshark)'''</center> | |||
| <center>'''Overhead (bit)'''</center> | |||
| <center>'''Packet/sec'''</center> | | <center style="background-color:#FFB6C1">'''Total Bit Rate (Kbit/sec)'''</center> | ||
| <center>'''Overhead | |||
| <center>'''Total Bit Rate | |||
|- | |- | ||
Line 183: | Line 196: | ||
| <center>13.551</center> | | <center>13.551</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>131.4</center> | | <center style="background-color:#FFB6C1">131.4</center> | ||
|- | |- | ||
Line 190: | Line 203: | ||
| <center>42.213</center> | | <center>42.213</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>393.46</center> | | <center style="background-color:#FFB6C1">393.46</center> | ||
|- | |- | ||
Line 197: | Line 210: | ||
| <center>6.7</center> | | <center>6.7</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>65.5</center> | | <center style="background-color:#FFB6C1">65.5</center> | ||
|- | |- | ||
Line 204: | Line 217: | ||
| <center>6.7</center> | | <center>6.7</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>65.5</center> | | <center style="background-color:#FFB6C1">65.5</center> | ||
|- | |- | ||
Line 211: | Line 224: | ||
| <center>20.28</center> | | <center>20.28</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>196.54</center> | | <center style="background-color:#FFB6C1">196.54</center> | ||
|- | |- | ||
Line 218: | Line 231: | ||
| <center>20.28</center> | | <center>20.28</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>196.54</center> | | <center style="background-color:#FFB6C1">196.54</center> | ||
|- | |- | ||
Line 225: | Line 238: | ||
| <center>16.46</center> | | <center>16.46</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>91.69</center> | | <center style="background-color:#FFB6C1">91.69</center> | ||
|- | |- | ||
Line 232: | Line 245: | ||
| <center>22.56</center> | | <center>22.56</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>149.05</center> | | <center style="background-color:#FFB6C1">149.05</center> | ||
|- | |- | ||
| <center>MPEG1 48KHz | | <center>MPEG1 48KHz quality 7, stereo</center> | ||
| <center>192</center> | | <center>192</center> | ||
| <center>27.81</center> | | <center>27.81</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>198.23</center> | | <center style="background-color:#FFB6C1">198.23</center> | ||
|- | |- | ||
Line 248: | Line 259: | ||
| <center>16.08</center> | | <center>16.08</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>99.6</center> | | <center style="background-color:#FFB6C1">99.6</center> | ||
|- | |- | ||
| <center>MPEG1 44.1KHz | | <center>MPEG1 44.1KHz quality 0, mono</center> | ||
| <center>65</center> | | <center>65</center> | ||
| <center>12.27</center> | | <center>12.27</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>67.75</center> | | <center style="background-color:#FFB6C1">67.75</center> | ||
|- | |- | ||
| <center>MPEG1 44.1KHz | | <center>MPEG1 44.1KHz quality 4, mono</center> | ||
| <center>90</center> | | <center>90</center> | ||
| <center>15.76</center> | | <center>15.76</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>93.53</center> | | <center style="background-color:#FFB6C1">93.53</center> | ||
|- | |- | ||
| <center>MPEG1 44.1KHz | | <center>MPEG1 44.1KHz quality 7, mono</center> | ||
| <center>140</center> | | <center>140</center> | ||
| <center>25</center> | | <center>25</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>145.6</center> | | <center style="background-color:#FFB6C1">145.6</center> | ||
|- | |- | ||
Line 282: | Line 287: | ||
| <center>5.8</center> | | <center>5.8</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>29.3</center> | | <center style="background-color:#FFB6C1">29.3</center> | ||
|- | |- | ||
Line 289: | Line 294: | ||
| <center>7.58</center> | | <center>7.58</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>45.7</center> | | <center style="background-color:#FFB6C1">45.7</center> | ||
|- | |- | ||
| <center>MPEG2 16KHz | | <center>MPEG2 16KHz quality 7, mono</center> | ||
| <center>64</center> | | <center>64</center> | ||
| <center>11.5</center> | | <center>11.5</center> | ||
| <center>224</center> | | <center>224</center> | ||
| <center>66.58</center> | | <center style="background-color:#FFB6C1">66.58</center> | ||
|} | |} | ||
'''RTP STREAMING MODE''' | '''RTP STREAMING MODE''' | ||
Line 323: | Line 325: | ||
'''Total Bit Rate (Kbit/sec) = Audio Data Rate (Kbit/sec) + Overhead/sec (Kbit/sec)''' | '''Total Bit Rate (Kbit/sec) = Audio Data Rate (Kbit/sec) + Overhead/sec (Kbit/sec)''' | ||
(Kbit = 1000 bit) | <sup>''(1 Kbit = 1000 bit)''</sup> | ||
{| class="wikitable" border="1" cellspacing="0" | {| class="wikitable" border="1" cellspacing="0" | ||
| <center>'''Audio Format'''</center> | | <center>'''Audio Format (VBR)'''</center> | ||
| <center>'''Audio Data Rate (Kbit/sec)'''</center> | | <center>'''Audio Data Rate (Kbit/sec)'''</center> | ||
| <center>'''Packet/sec (Wireshark)'''</center> | | <center>'''Packet/sec (Wireshark)'''</center> | ||
| <center>'''Overhead (bit)'''</center> | | <center>'''Overhead (bit)'''</center> | ||
| <center style="background-color:#FFB6C1">'''Total Bit Rate (Kbit/sec)'''</center> | | <center style="background-color:#FFB6C1">'''Total Bit Rate (Kbit/sec)'''</center> | ||
|- | |- | ||
Line 356: | Line 350: | ||
|- | |- | ||
| <center>MPEG1 48KHz | | <center>MPEG1 48KHz quality 7, stereo</center> | ||
| <center>192</center> | | <center>192</center> | ||
| <center>41.7</center> | | <center>41.7</center> | ||
Line 370: | Line 364: | ||
|- | |- | ||
| <center>MPEG1 44.1KHz | | <center>MPEG1 44.1KHz quality 0, mono</center> | ||
| <center>65</center> | | <center>65</center> | ||
| <center>38.3</center> | | <center>38.3</center> | ||
Line 377: | Line 371: | ||
|- | |- | ||
| <center>MPEG1 44.1KHz | | <center>MPEG1 44.1KHz quality 4, mono</center> | ||
| <center>90</center> | | <center>90</center> | ||
| <center>38.3</center> | | <center>38.3</center> | ||
Line 384: | Line 378: | ||
|- | |- | ||
| <center>MPEG1 44.1KHz | | <center>MPEG1 44.1KHz quality 7, mono</center> | ||
| <center>140</center> | | <center>140</center> | ||
| <center>38.3</center> | | <center>38.3</center> | ||
Line 405: | Line 399: | ||
|- | |- | ||
| <center>MPEG2 16KHz | | <center>MPEG2 16KHz quality 7, mono</center> | ||
| <center>64</center> | | <center>64</center> | ||
| <center>27.8</center> | | <center>27.8</center> | ||
Line 414: | Line 408: | ||
{| class="wikitable" border="1" cellspacing="0" | |||
| <center>'''Audio Format (STL)'''</center> | |||
| <center>'''Audio Data Rate (Kbit/sec)'''</center> | |||
| <center>'''Packet/sec (Wireshark)'''</center> | |||
| <center>'''Overhead (bit)<sup>1'''</sup>'''</center> | |||
| <center style="background-color:#FFB6C1">'''Total Bit Rate (Mbit/sec)<sup>2'''</sup>'''</center> | |||
|- | |||
| <center>ALaw 8 Khz, mono</center> | |||
| <center>64</center> | |||
| <center>50</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.09</center> | |||
|- | |||
| <center>PCM MSB 16 bit 8 KHz mono</center> | |||
| <center>128</center> | |||
| <center>50</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.16</center> | |||
|- | |||
| <center>PCM MSB 16 bit 11.025 KHz mono</center> | |||
| <center>176.4</center> | |||
| <center>50</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.2</center> | |||
|- | |||
| <center>PCM MSB 16 bit 12 KHz mono</center> | |||
| <center>192</center> | |||
| <center>50</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.22</center> | |||
|- | |||
| <center>PCM MSB 16 bit 16 KHz mono</center> | |||
| <center>256</center> | |||
| <center>50</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.29</center> | |||
|- | |||
| <center>PCM MSB 16 bit 22.050 KHz mono</center> | |||
| <center>352.8</center> | |||
| <center>50</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.38</center> | |||
|- | |||
| <center>PCM MSB 16 bit 24 KHz mono</center> | |||
| <center>384</center> | |||
| <center>50</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.41</center> | |||
|- | |||
| <center>PCM MSB 16 bit 32 KHz mono</center> | |||
| <center>512</center> | |||
| <center>50</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.54</center> | |||
|- | |||
| <center>PCM MSB 16 bit 44.1 KHz mono</center> | |||
| <center>705.6</center> | |||
| <center>70</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.75</center> | |||
|- | |||
| <center>PCM MSB 16 bit 48 KHz mono</center> | |||
| <center>768</center> | |||
| <center>75</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.81</center> | |||
|- | |||
| <center>PCM MSB 16 bit 8 KHz stereo</center> | |||
| <center>256</center> | |||
| <center>50</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.29</center> | |||
|- | |||
| <center>PCM MSB 16 bit 11.025 KHz stereo</center> | |||
| <center>352.8</center> | |||
| <center>50</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.38</center> | |||
|- | |||
| <center>PCM MSB 16 bit 12 KHz stereo</center> | |||
| <center>384</center> | |||
| <center>50</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.41</center> | |||
|- | |||
| <center>PCM MSB 16 bit 16 KHz stereo</center> | |||
| <center>512</center> | |||
| <center>50</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.54</center> | |||
|- | |||
| <center>PCM MSB 16 bit 22.050 KHz stereo</center> | |||
| <center>705.6</center> | |||
| <center>70</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.75</center> | |||
|- | |||
| <center>PCM MSB 16 bit 24 KHz stereo</center> | |||
| <center>768</center> | |||
| <center>75</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">0.81</center> | |||
|- | |||
| <center>PCM MSB 16 bit 32 KHz stereo</center> | |||
| <center>1024</center> | |||
| <center>100</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">1.08</center> | |||
|- | |||
| <center>PCM MSB 16 bit 44.1 KHz stereo</center> | |||
| <center>1411.2</center> | |||
| <center>137</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">1.5</center> | |||
|- | |||
| <center>PCM MSB 16 bit 48 KHz stereo</center> | |||
| <center>1536</center> | |||
| <center>150</center> | |||
| <center>620</center> | |||
| <center style="background-color:#FFB6C1">1.63</center> | |||
|} | |||
<sup>''1 - in PCM and A/uLaw streaming mode, there is not MPA wrapper.''</sup> | |||
<sup>''2 - 1 Mbit = 1000 Kbit.''</sup> | |||
'''Without Ethernet Overhead''' | '''Without Ethernet Overhead''' | ||
{| class="wikitable" border="1" cellspacing="0" | {| class="wikitable" border="1" cellspacing="0" | ||
| <center>'''Audio Format'''</center> | | <center>'''Audio Format (VBR)'''</center> | ||
| <center>'''Audio Data Rate (Kbit/sec)'''</center> | | <center>'''Audio Data Rate (Kbit/sec)'''</center> | ||
| <center>'''Packet/sec (Wireshark)'''</center> | | <center>'''Packet/sec (Wireshark)'''</center> | ||
| <center>'''Overhead (bit)'''</center> | | <center>'''Overhead (bit)'''</center> | ||
| <center style="background-color:#FFB6C1">'''Total Bit Rate (Kbit/sec)'''</center> | | <center style="background-color:#FFB6C1">'''Total Bit Rate (Kbit/sec)'''</center> | ||
|- | |- | ||
Line 448: | Line 579: | ||
|- | |- | ||
| <center>MPEG1 48KHz | | <center>MPEG1 48KHz quality 7, stereo</center> | ||
| <center>192</center> | | <center>192</center> | ||
| <center>41.7</center> | | <center>41.7</center> | ||
Line 462: | Line 593: | ||
|- | |- | ||
| <center>MPEG1 44.1KHz | | <center>MPEG1 44.1KHz quality 0, mono</center> | ||
| <center>65</center> | | <center>65</center> | ||
| <center>38.3</center> | | <center>38.3</center> | ||
Line 469: | Line 600: | ||
|- | |- | ||
| <center>MPEG1 44.1KHz | | <center>MPEG1 44.1KHz quality 4, mono</center> | ||
| <center>90</center> | | <center>90</center> | ||
| <center>38.3</center> | | <center>38.3</center> | ||
Line 476: | Line 607: | ||
|- | |- | ||
| <center>MPEG1 44.1KHz | | <center>MPEG1 44.1KHz quality 7, mono</center> | ||
| <center>140</center> | | <center>140</center> | ||
| <center>38.3</center> | | <center>38.3</center> | ||
Line 497: | Line 628: | ||
|- | |- | ||
| <center>MPEG2 16KHz | | <center>MPEG2 16KHz quality 7, mono</center> | ||
| <center>64</center> | | <center>64</center> | ||
| <center>27.8</center> | | <center>27.8</center> | ||
Line 504: | Line 635: | ||
|} | |} | ||
{| class="wikitable" border="1" cellspacing="0" | |||
| <center>'''Audio Format (STL)'''</center> | |||
| <center>'''Audio Data Rate (Kbit/sec)'''</center> | |||
| <center>'''Packet/sec (Wireshark)'''</center> | |||
| <center>'''Overhead (bit)<sup>1'''</sup>'''</center> | |||
| <center style="background-color:#FFB6C1">'''Total Bit Rate (Mbit/sec)<sup>2'''</sup></center> | |||
|- | |||
| <center>ALaw 8 Khz, mono</center> | |||
| <center>64</center> | |||
| <center>50</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.08</center> | |||
|- | |||
| <center>PCM MSB 16 bit 8 KHz mono</center> | |||
| <center>128</center> | |||
| <center>50</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.14</center> | |||
|- | |||
| <center>PCM MSB 16 bit 11.025 KHz mono</center> | |||
| <center>176.4</center> | |||
| <center>50</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.2</center> | |||
|- | |||
| <center>PCM MSB 16 bit 12 KHz mono</center> | |||
| <center>192</center> | |||
| <center>50</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.2</center> | |||
|- | |||
| <center>PCM MSB 16 bit 16 KHz mono</center> | |||
| <center>256</center> | |||
| <center>50</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.27</center> | |||
|- | |||
| <center>PCM MSB 16 bit 22.050 KHz mono</center> | |||
| <center>352.8</center> | |||
| <center>50</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.36</center> | |||
|- | |||
| <center>PCM MSB 16 bit 24 KHz mono</center> | |||
| <center>384</center> | |||
| <center>50</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.4</center> | |||
|- | |||
| <center>PCM MSB 16 bit 32 KHz mono</center> | |||
| <center>512</center> | |||
| <center>50</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.52</center> | |||
|- | |||
| <center>PCM MSB 16 bit 44.1 KHz mono</center> | |||
| <center>705.6</center> | |||
| <center>70</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.72</center> | |||
|- | |||
| <center>PCM MSB 16 bit 48 KHz mono</center> | |||
| <center>768</center> | |||
| <center>75</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.8</center> | |||
|- | |||
| <center>PCM MSB 16 bit 8 KHz stereo</center> | |||
| <center>256</center> | |||
| <center>50</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.27</center> | |||
|- | |||
| <center>PCM MSB 16 bit 11.025 KHz stereo</center> | |||
| <center>352.8</center> | |||
| <center>50</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.36</center> | |||
|- | |||
| <center>PCM MSB 16 bit 12 KHz stereo</center> | |||
| <center>384</center> | |||
| <center>50</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.4</center> | |||
|- | |||
| <center>PCM MSB 16 bit 16 KHz stereo</center> | |||
| <center>512</center> | |||
| <center>50</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.52</center> | |||
|- | |||
| <center>PCM MSB 16 bit 22.050 KHz stereo</center> | |||
| <center>705.6</center> | |||
| <center>70</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.72</center> | |||
|- | |||
| <center>PCM MSB 16 bit 24 KHz stereo</center> | |||
| <center>768</center> | |||
| <center>75</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">0.8</center> | |||
|- | |||
| <center>PCM MSB 16 bit 32 KHz stereo</center> | |||
| <center>1024</center> | |||
| <center>100</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">1.05</center> | |||
|- | |||
| <center>PCM MSB 16 bit 44.1 KHz stereo</center> | |||
| <center>1411.2</center> | |||
| <center>137</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">1.45</center> | |||
|- | |||
| <center>PCM MSB 16 bit 48 KHz stereo</center> | |||
| <center>1536</center> | |||
| <center>150</center> | |||
| <center>320</center> | |||
| <center style="background-color:#FFB6C1">1.58</center> | |||
|} | |||
<sup>''1 - in PCM and A/uLaw streaming mode, there is not MPA wrapper.''</sup> | |||
<sup>''2 - 1 Mbit = 1000 Kbit.''</sup> | |||
The PDF version of the original document is downloadable here [[[[media:bit_rate_calculation_3_0.pdf]]]]. | |||
Back to [[FAQ]] | Back to [[FAQ]] |
Latest revision as of 11:55, 7 June 2013
BIT RATE CALCULATION WITH BARIX DEVICES
With this document we want to explain how to calculate the total bit rate flowing on an Ethernet cable connected to a Barix device.
The total bit rate is equal at the audio bit rate plus the overhead due to the encapsulation of audio packet inside the layers of OSI stack [1].
We have used for the test an Instreamer 100 (with standard firmware) configured first in RAW UDP and then in RTP, and an Exstreamer 1000 (with STL firmware).
RAW UDP STREAMING MODE
For the structure of the Ethernet packet see here: [2]
The Total Ethernet Overhead per packet is 300 bit.
For the structure of the IP packet see here: [3]
The Total IP Overhead per packet is 160 bit.
For the structure of the UDP packet see here: [4]
The Total UDP Overhead per packet is 64 bit.
Total Bit of Overhead per Packet = Ethernet Overhead + IP Overhead + UDP Overhead = 524 bit
The Audio Bit rate is expressed in bit/sec but the Overhead is expressed in bit/packet.
So we have to translate the Overhead (bit/packet) in Overhead rate (bit/sec).
For this we need to know the amount of packet/sec, that depends by Audio Format and is measurable with Network Protocol Analyzer software like Wireshark.
The values of Audio Data for audio format, sampling frequency and quality (MP3 bitrate average), come from Instreamer Manual (firmware V3.10 – page 18 - [5])
For MPEG1/2 Layer3 (MP3) bit rate
the following Encoding range is supported as Constant & Variable Bit Rate in IPAM102 based devices (e.g. new Instreamer):
28kbps (MPEG2@16KHz mono) - 320kbps (MPEG1@48KHz stereo)
the following Encoding range is supported as Variable Bit Rate in IPAM100 based devices (e.g. old Instreamer100):
28kbps (MPEG2@16KHz mono) - 192kbps (MPEG1@48KHz stereo)
Decoding range on both IPAM100 and IPAM300 as Constant or Variable Bit Rate is:
8kbps (MPEG2) - 320kbps (MPEG1)
Overhead/sec = Overhead/Packet x Packet/sec
Total Bit Rate (Kbit/sec) = Audio Data Rate (Kbit/sec) + Overhead/sec (Kbit/sec)
(1 Kbit = 1000 bit)
Without Ethernet Overhead
RTP STREAMING MODE
For the structure of the RTP packet see here: [6]
The Total RTP Overhead per packet is 128 bit (counting also the MP3 MPA wrapper inside the RTP payload, which has an extra 32 bit header).
Total Bit of Overhead per Packet =
Ethernet Overhead + IP Overhead + UDP Overhead + RTP Overhead = 652 bit
The values of Audio Data for audio format, are the same of above, since the transmission protocol doesn't affect audio bit rate.
Overhead/sec = Overhead/Packet x Packet/sec
Total Bit Rate (Kbit/sec) = Audio Data Rate (Kbit/sec) + Overhead/sec (Kbit/sec)
(1 Kbit = 1000 bit)
1 - in PCM and A/uLaw streaming mode, there is not MPA wrapper.
2 - 1 Mbit = 1000 Kbit.
Without Ethernet Overhead
1 - in PCM and A/uLaw streaming mode, there is not MPA wrapper.
2 - 1 Mbit = 1000 Kbit.
The PDF version of the original document is downloadable here [[media:bit_rate_calculation_3_0.pdf]].
Back to FAQ