在线座谈

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精彩问答

主题:CD/MP3/WMA便携式播放机设计讲座
在线问答
[问:liuhengjie] 请问 cirrus logic 有哪些mp3/wma的解码芯片,有没有功能更强大的芯片,比如集成有mcu核或dac的mp3/wma单片解决方案? 
[答:Mark] At Cirrus we have two integrated solutions for WMA/MP3 systems.  For CD MP3 players we have the CS7410, and for solid state and hard drive playes Cirrus has the EP7312 solution.  [2003-8-21 10:26:12]
[问:qiangwa] 请问EP7312如何接LCD? 
[答:Mark] The EP312 has an integrated LCD controller that can drive a wide number of displays.  For small displays the EP7312 can connect to the axternal controller/line driver.  [2003-8-21 10:28:21]
[问:luosiguo] 请问在设计中如何保证产品ESD和EMC测试合格呢?谢谢! 
[答:Michael] ESD:注意外部接口和结构件的设计,尤其是结构件的缝隙。EMC:最关键的是找到EMC不良的源头,一般是晶振,SDRAM,主CPU PLL;还要注意耳机带来的辐射。PCB板走线要短,信号幅度尽可能低,同时采用机壳接地、共模抑制线圈和磁珠。  [2003-8-21 10:30:20]
[问:lijianguo] 1. MP3播放器存储体的选型.2.如何任意选择存储体中的MP3节目,选曲的硬件及软件实现原理. 
[答:Mark] The EP7309/EP7312 from Cirrus can be connected to NAND Flash, NOR Flash DRAM or SRAMFor playlists the software uses the ending of the file name, *.pls for example, to understand how to interpret the playlist.  Cirrus audio application software includes support for all common play-list formats  [2003-8-21 10:32:00]
[问:杨_64J7U] CD/MP3/WMA便携式播放机设计采用的解码芯片是哪个公司的,什么型号?谢谢! 
[答:Peter] CS7410 from Cirrus Logic, Inc.  [2003-8-21 10:33:19]
[问:ponywang] 与其它品牌的同类解决方案相比,CIRRUS LOGIC产品的优势是什么? 
[答:Mark] Cirrus logic decoder solutions integrate both the microprocessor and the DSP functionality in a single chip, and are provided with a complete player application.  The extra integration of the Cirrus solutions leads to products that have longer battery life, and have a lower BOM cost.  [2003-8-21 10:33:39]
[问:lilidong] 设计便携式CD/MP3时选择光头和servo system时有何考虑? 对不同光头有何比较? 
[答:Larry] When choosing servo system, major consideration include 1.  selection of OPU motor type (brushless vs DC     motor), CD, CD-RW optical pickup capability,     kick-start current, continuous spinning     current)2.  motor driver and RF amplifier are also important.  Motor driver selection must match the OPU motor type.  Power consumption is important.  Some motor driver also include DC/DC converter, audio DAC and remote control input.3.  Servo DSP (or CD-DSP) is perhaps the most complex unit in a servo system.  It handles C1/C2 error checking and decodes audio frames.Power consumption is perhaps the most important consideration for servo system.  [2003-8-21 10:34:23]
[问:tanke] 怎樣有效消除EL電路和MCU電路對收音電路的干擾 
[答:Michael] 将数字器件和Tuner高频模拟器件尽可能分开摆放,数字地和模拟地连通点小心处理。在收音电路工作的时候,将不需要的数字器件,包括CD Servo停止工作。  [2003-8-21 10:34:51]
[问:lwbence] 在便携系统产品的开发当中,通常对功耗的考虑很重要,从这个考虑出发在实际设计当中有没有什么技巧或规定 
[答:Michael] 没有具体的规定,根据客户的要求。具体技巧请参见我们的Presentation.  [2003-8-21 10:35:50]
[问:chinagreatman] 我以前用CS7410/Koala的CD接口坐位录音接口,用它的I2S接口连接DAC。功能可以实现就是录音效果差。有刺耳的噪音,噪音源有那些呢?如何改进呢? 
[答:Larry] CS7410 audio noise could be related to cross-over noise from digital circuit, recorded noise in the original audio stream, pop-noise caused by not muting the circuit during startup.  Poor PCB layout could also be a contributing factor.There could be a variety of possibilities, depending on your specific implementation.  [2003-8-21 10:38:07]
[问:timorthy] 在cs7410芯片中,是否集成现成的mp3解码算法? 
[答:Larry] Yes.  [2003-8-21 10:38:55]
[问:afeng] 分别用1M x 16和4M x 16的SDRAM可以做到多少防震时间(CD&MP3&WMA) 
[答:Mark] For 16mbit DRAM the Cirrus solution can implement approximately 40s of ESP, and for 64Mbit of DRAM the solution can achieve 160s for CDDA playback, and more cor compressed audio depending on the bit-rate of the compressed music.  [2003-8-21 10:39:42]
[问:timorthy] 在使用cs7410的系统中,是否还要使用其他的控制芯片来完成整个的mp3播放机设计? 
[答:Larry] CS7410 serves both as system controller and decoder.  It only requires memory and servo chipset to complete a MP3 solution.  [2003-8-21 10:40:57]
[问:老虎] 请问如果采用Cirrus 的EP7312,以后固件能升级吗,比如我想加入对AAC解码的支持。 
[答:Larry] Cirrus has an AAC decoder solution for EP7312.  [2003-8-21 10:41:47]
[问:zhnyong] 为什么说DSP算法要用32位或是24位,才能满足ADC的16位的精度要求呢? 
[答:Mark] During intermediate processing it is necessary to perform many computations for ESP, decompression etc.  If all of these computations are performed using 16 bits the the accuracy of the output signal may be as low as 13-14 bits by the time it reaches the ADC.  Using 24 or 32 bits for computations enables dynamic range to be preserved in internal calculations ensuring that the output quality is fully 16-bit audio.  [2003-8-21 10:42:31]
[问:momingsz771226] 1. 请问针对EMC测试,在硬件设计中具体需要注意些什么? 谢谢! 2. 在不影响性能的前提下,线径最小可以允许多大?3. 针对本身解码噪音比较大的MP3 DECODER IC,在外围电路上有什么办法可以见小噪音,提高信噪比.谢谢! 
[答:Michael] 1. 请参见上一个对ESD和EMC问题的解答。2. 根据板的大小和器件密度、器件封装而定。3. MP3 Decoder不会带来解码噪音,如果不使用内置的Audio DAC,因为是数字信号的处理。对于MP3 decoder,关键是要选择优秀的DSP算法。然后采用高信噪比的Audio DAC,同时注意信号的布线,同时防止电源的干扰影响信噪比。  [2003-8-21 10:44:02]
[问:cssun] 请问关于产品的电池是使用充电电池好,还是使用碱性电池好?如果使用充电电池那么充电是在设备内部好,还是用外部的充电器好? 
[答:Larry] CS7410 portable CD-MP3 solution can use either rechargeable battery (NiCd or NiMH) or Alkaline.  Rechargeable batteries such as NiMH has constant discharge curve, while Alkaline has a linear discharge curve.  If you use Akaline battery, you need to make sure the current requirement is not too great.Most "flat" CD/MP3 player using rechargeables, the charger is build-in as a part of the player.  [2003-8-21 10:46:01]
[问:adlion] 请问贵公司的EP7309提供的开发支持如何?贵公司是否提供mp3的编解码程序以及相关的文件系统支持?谢谢! 
[答:Mark] For the EP73xx family of processors, Cirrus has an MP3 encoder available that operates in real time using the 90MHz versions of these processor.Cirrus reference software contains a file system for use with Flash memory and a HDD file system is being worked on.For the CS7410, the Cirrus application software has support for all CD file systems includding ISO9660 and UDF.  [2003-8-21 10:48:03]
[问:老虎] 我想请问一下夏先生:   对于一款Mp3解码芯片,如何来测试他的音质,有没有标准的测试码流来验证,他的解码精度是如何界定的?   谢谢! 
[答:Michael] 我不确认是否有标准的MP3测试码流,但可以自制测试码流,然后进行主观评价。Mp3解码芯片负责将Mp3压缩数据转换为PCM数据流,所以解码精度是由解码软件和Audio DAC一起来决定的。  [2003-8-21 10:48:21]
[问:samire] Cirrus Logic的音频处理器7410的功耗,和其它公司同类产品相比之下,在什么样的水平上? 
[答:Mark] CS7410 based solutions have very competitive power consumption in comparison to competing low cost solutions.  However, there is great dependency on the power consumption of the DSP servo, motor driver, and loader mechanism that is used to complete the player.  [2003-8-21 10:50:13]
[问:zhnyong] 请您简单的说明一下动态调整主处理器频率的方法,或是举一个相关的系统应用实例!谢谢! 
[答:Michael] 例如,主处理器在处理高数传率的WMA码流时需要的系统带宽要高于处理CDDA码流,所以在系统播放CDDA时,可以降低系统主频。  [2003-8-21 10:50:55]
[问:GOOF] 请问声音变速的原理,软件是怎么样实现的.重放的时候听见声音明显慢了很多,(声调也没变)但用测试频率结果没变. 
[答:Larry] Sample rate conversation usually converse 44.1kHz to 48kHz audio, or vise versa.  There are the two most popular ones.  All recorded audio has a sample rate associated with it.  The decoder must also decode the audio and produce output at the right sample rate.  Sometimes the output DAC also has a sample rate requirement.  If any of these do not match, you can get apparent audio "slow-down".  It is important to use sample rate converter to match the sample rate.  [2003-8-21 10:51:58]
[问:ponywang] 如何最大限度地优化硬件和软件设计以降低整机功耗,延长电池使用寿命? 
[答:Mark] It is necessary to design the player hardware and the player software such that the player software can control the power to components that are not in use.  For instance, power can be cut off from the loader mechanism when the CD player is playing from ESP memory.  Cirrus has invested much engineering effor in tuning the power control capabilities of the application SW.  [2003-8-21 10:53:08]
[问:samire] 演示中所将PCB布线后要进行优化,是否有专门的软件进行?什么工具? 
[答:Michael] PCB绘图软件一般都会带有优化工具,但优化的结果是否令人满意就难以确定了。  [2003-8-21 10:53:18]
[问:afeng] 有设计实例提供吗?CS7410的DATA SHEET,电路图等,配哪一个伺服好?CXA3068 or SAA7824(PHILIPS) 
[答:Michael] 我们现在可以提供三种伺服的参考设计: Sony, Rohm, Philips.  [2003-8-21 10:54:11]
[问:liuhengjie] CS7410内置的32bit RISC处理器是那种指令系统? 
[答:Michael] 精简指令系统  [2003-8-21 10:55:16]
[问:ecnanjing_EBY7E] 好的音响的动态范围要达到110dB,而刚才介绍的DAC的动态范围只不过是80dB,如何保证音质? 
[答:Mark] It is important to match the cost/quality of the DAC used to the application in which it is used.  For portable applications, music is usually listened to in a noisy environment, such as a bus or a train, using inexpensive headphones.  In this environment one cannot hear the improved quality of a 110dB SNR and hence a lower cost solution using an 80dB DAC will often be selected by a manufacturer.  [2003-8-21 10:55:59]
[问:ljp] 请介绍44L10中的D类放大器的具体结构和功能及效率. 
[答:Peter] Please visit www.cirrus.com for detailed datasheet. thank you.  [2003-8-21 10:56:26]
[问:xjy223322] 您好!    人们在使用过程中往往发现,无论是CD还是MP3,其音质与耳机质量的关系十分密切,请问在进行高音质设计和音质测试时对此有什么对策和要求。 
[答:Larry] Quality audio is intimately connected to headphone impedance.  Usually one should adjust the output (analog) stage to match the headphone impedance.  -Larry  [2003-8-21 10:56:40]
[问:afeng] 请问CS7410可以做到带ID3功能吗?怎样实现?设计方案可以提供吗? 
[答:Michael] CS7410可以支持ID3和内嵌歌词,已经包含在设计参考方案中。  [2003-8-21 10:56:47]
[问:timorthy] 购买并使用cs7410,cirrus是否提供现成的mp3播放机设计方案? 
[答:Mark] Cirrus has working reference designs that can be re layed out to fit within a customers ID.  [2003-8-21 10:57:00]
[问:ecnanjing_EBY7E] Cirrus Logic MP3能支持多少外存储卡? 
[答:Larry] Cirrus ARM7 and ARM9 products can support CF, MMC, Smart Media.  [2003-8-21 10:58:04]
[问:ken999] Koala的功耗怎么样?mp3 decoder 在多少Mhz运行? 
[答:Mark] The power consumption and MHz of the CS7410 varies depending on the decoder and other settings.  CS7410 power consumption is very competitive for low cost CD-MP3 players.  [2003-8-21 10:59:11]
[问:老虎] 请问Cirrus的CD/Mp3/WMA解码芯片中的Dsp的运算精度是多少位的,他的输出精度是16位吗? 
[答:Larry] Cirrus CS7410 DSP core is 16-bit operands with 32-bit accumulator for better precision result.  [2003-8-21 11:01:11]
[问:randysz] 省电好坏关键取决于DSP,贵公司外围省电器件究竟可以在多大程度上发挥功效? 
[答:Mark] The most important aspect for saving power in a system like a CD-MP3 player is to be able to minimize power to the motor driver, loader mechanism, and DSP servo, while these components are not in use during ESP playback.  Typically, in a CD-MP3 player these external components take much more power than the DSP, and hence external power control can be more important than the power consumed in the DSP.  [2003-8-21 11:01:52]
[问:zeit] 1、请问目前的CD系统除了16位pcm以外,是否还支持更高分辨率?如18bit/20/24bit?2、是否能够支持HDCD解码?3、DVD格式的解码有现成方案吗? 
[答:Larry] 1. CS7410 solution can support 24-bit PCM.2. Current HDCD is not supported3. No DVD audio, but VCD audio is supported  [2003-8-21 11:02:20]
[问:zhsxjtu] 目前关于音频压缩/解码的标准更新较快。如果接收机的核心部分用ASIC来做,就无法适应市场的不断变化。如果用PLD来做的话,有何更好的、能在功耗价格上达到最优的解决方案? 
[答:Michael] 一般不会选用PLD。常规的设计是采用ASIC或是32/16位CPU,但同时需要Firmware(微码).这样既有不可更改的硬件平台作为基础,但Firmware可以很方便地升级,具有灵活性,或是将Firmware外挂。这样需要支持新的音频标准时,只要更新微码就可以了。  [2003-8-21 11:02:31]
[问:wei_wei] 请问:能否实现ADPCM录音功能? 
[答:Larry] CS7410 firmware supports ADPCM  [2003-8-21 11:03:00]
[问:randysz] 请问WMA格式音乐发展前景如何?它会取代MP3格式而成为主流么? 
[答:Mark] Many consumers who use Microsoft XP based machines use WMA because it is supported natively by the OS.  People still call the files MP3 files, even though they are WMA files.  Failure to support WMA for such customers may lead to store returns which is not good for product profitability.  [2003-8-21 11:04:22]
[问:lijianguo] CIRRUS 的EP7312无USB接口,请问贵公司是否有带USB接口的解码芯片?今后的新品是否将考虑内置合适的高速下载接口? 
[答:Larry] EP7312 does not have on chip USB support. But there is a reference design that integrates EP7312 with USB 1.1 device.  There is plan to update that reference design to USB 2.0 device.  [2003-8-21 11:04:56]
[问:ljp] 对MP3来说,你认为采用几种电源输出有利于省电? 
[答:Michael] 为了提高电池的寿命,最好能分别控制不同模块的供电,以便在需要的时候关闭不需使用的模块。分别供电以下模块:1. 主CPU PLL;(一般为1.8V)2. 主CPU IO Pins;(一般为3.3V)3. SDRAM/Flash4. Servo DSP5. OPU7. Motor driver  [2003-8-21 11:07:00]
[问:mintea] 请问:该设计能播放48KHz,320Kbps的MP3 bitstreams吗 
[答:Larry] CS7410 can support 48kHz sample rate and 320Kbps encoding bit rate  [2003-8-21 11:07:01]
[问:even] 你好:    请问使用的芯片与USB的传输速率的关系和最大限度地延长电池寿命的问题? 
[答:Larry] EP7309 and EP7312 will work with external USB 1.1 device for transfer speed up to 12 Mbps.  There is currently no USB solution for CS7410.  [2003-8-21 11:08:53]
[问:rong_zeng] 1、Cirrus Logic提供从硬件到软件的全面解决方案吗?软件是否提供源码?软件的开发平台是什么,编译工具是什么?使用的嵌入式操作系统是什么?2、能否详细介绍一下贵公司音频处理器的特点,比如内部DSP是多少位的,内部SRAM和CACHE有多少,有哪些外围接口,频率和MIPS最多是多少等。3、现在采用贵公司解决方案的厂商多吗?能否列举一些比较大的厂商? 
[答:Mark] The Cirrus CD MP3 player solution is designed to work with an OS, but does not need one, in order to ensure that our customers do not have to pay for an OS.  Cirrus logic has a complete development platform and a number of reference designs covering different DSP Servos and loader mechanisms.  The core processor is a MIPS architecture RISC processor.  The software is all written in C and can be created using many powerful software development tools that are available for MIPS based microcontrollers.Cirrus provide a reference UI in source code that can be used as the basis for Cirrus"s customers to create 1st class products.For more detailed information download the data sheet from www.cirrus.com, or contact our sales representatives.  [2003-8-21 11:10:02]
[问:tinyor] 您好,对于便携式播放器的存储器现在一般用Flash Memory, 请问:对于存储器类型选择上(Nor/Nand Flash?),各有什么利弊?除了读写时间、写入功耗、扇区大小外,还需要考虑些什么?还有更好的其它类型的存储器可以选用么?  谢谢! :) 
[答:Michael] NOR适合用来存贮代码,NAND适合用来存储数据。  [2003-8-21 11:10:39]
[问:zhnyong] CS7410内部运算的位数是多少位? 
[答:Michael] 32 bit.  [2003-8-21 11:10:49]
[问:samire] 7410有没有动态处理时钟频率的功能? 
[答:Mark] Yes, the application that is provided by Cirrus uses this capability.  [2003-8-21 11:11:25]
[问:老虎] 我想请问一下关于Mp3解码芯片设计方面的问题,就是如何测试一款解码芯片的解码精度? 
[答:Larry] To test the accuracy of MP3 decoder, take the original audio in PCM and compare with the decoded audio in PCM.  Use Audio Analyzer to compare the two wave forms.  You can use simple test tone to complex audio wave form as test audio stream.  [2003-8-21 11:11:33]
[问:liutang2] 是否可以扩展便携式设备的功能,如可以存储一些文本文件,用来进行电子图书阅读。 
[答:Mark] For the EP73xx product line many other types of products have been made including electronic books, fingerprint scanners, digital photograph frames ...  [2003-8-21 11:13:17]
[问:ken999] 请问如果跟ess3890或者sunplus716相比cs7410还能说是low cost吗?不出有什么优点体现? 
[答:Mark] Cirrus customers have compared the BOM of a CS7410 solution with that of our competitors, and our customers are excited to use the CS7410 based solution.  [2003-8-21 11:15:22]
[问:86222] CD/MP3音频解码方面有没有采用segma-delta的DAC? 
[答:Larry] Yes, CS7410 has an internal sigma-delta DAC.  [2003-8-21 11:16:01]
[问:ken999] cs7410带FM/AM的DTS怎么样实现? 
[答:Mark] CS7410 based solutions with AM/FM are available.  The CS7410 is a very flexible processor and can be used to create a wide range of differentiated CD-MP3 player products.  [2003-8-21 11:17:36]
[问:ken999] 请问夏先生,cs7410的市场价格?有什么优点与ess3890W相比? 
[答:Mark] In comparing prices it is important to compare the BOM cost rather than the chip cost.  Due to its high level of integration the system BOM of CS7410 based solutions is very competitive.  Please contact our sales representatives who can give you more information on our chip and BOM costs.  [2003-8-21 11:19:40]
[问:老虎] 我想请问马克?爱瑞顿博士:  在不增加芯片的运算字长或运算的复杂度的前提下,在系统设计阶段,如何提高Mp3解码芯片的音质,也就是本讲座所说的高音质设计?  谢谢! 
[答:Larry] Without increasing word size, other means to increase MP3 audio quality may include use of SBR (spectual band replication), such as in MP3Pro.  But audio is more than just decoding, it is also related to faith replication of original content.  So good analog output stage design, clean mute circuit (perhaps including auto-mute), are also very important in good audio quality.  [2003-8-21 11:20:38]
[问:xytao_800211] 专家您好!   请问在设计CD/MP3/WMA便携式播放机时,PCB在LAYOUT过程中应分别注意哪些?另,如何提高其稳定性.FROM:ROBIN 
[答:Michael] 具体请参见我们的Presentation.  [2003-8-21 11:22:25]
[问:ecnanjing_EBY7E] 请问专家,Cirrus的MP3能否播放32Kbps,16Kbps的ADPCM(A-LAW or u-LAW)语音? 
[答:Larry] CS7410 firmware contains 4:1 ADPCM encode and decode, and can easily support A-Law/u-Law audio.  [2003-8-21 11:22:56]
[问:samking] 如何加强MP3的防震问题? 
[答:Mark] The CS7410 contains special patern matching hardware which when used with C1, C2, C3 error detection can be used to quickly detect a shock and accurately resynchronize the lazer to ensure high performance ESP.  [2003-8-21 11:23:08]
[问:wlphenix] 请问现在大多数MP3不能对WAV进行解码,那么如何实现? 
[答:Mark] A .WAV file is simply PCM data, and all Cirrus software solutions are capable of playing back this type of file.  [2003-8-21 11:24:20]
[问:tinyor] 相信不少做便携产品的人,是从做MCU应用系统入手的,往往对音频部分的设计比较缺乏经验,烦请专家对上述情况的人该如何着手设计音频电路重点给些指点,谢谢! :) 
[答:Michael] 1. Audio 各种格式的特点;2. Audio DAC 和放大部分的PCB设计,包括模拟信号和数字信号的干扰;3. Audio输出的定量测试;4. 注意从软件和硬件设计的角度来降低系统功耗;  [2003-8-21 11:25:06]
[问:rnwinston] 请问你们哪个给我一个方案可以吗?我们公司有意思生产MP3方面的产品 
[答:Mark] Please contact Cirrus Logic sales reprasentatives who can help you to make your own solution, or who can put you in contact with design houses or ODMs creatinf CS7410 based CD-MP3 player solutions.  [2003-8-21 11:26:06]
[问:jacklin] 1、Cirrus Logic公司提供的数字化娱乐产品的半导体芯片解决方案对电子设计爱好者的吸引力在哪些方面?2、贵公司是否会向电子设计爱好者提供一些价格能被接受的实验电路模块? 
[答:Larry] 1.  Cirrus digital entertainment solution is attractive because Cirrus offers complete solution, including system software and silicon.  The silicon usually offer high integration of important components.  For example, CS7410 has built in MP3/WMA feature.2.  Cirrus sells reference platforms for our audio and video products.  [2003-8-21 11:26:30]
[问:zhnyong] 请问CS7410上电后必须有做的初始化工作是什么? 需不需要加入MCU对CS7410进行初始化? 
[答:Michael] 初始化包括RTOS的导入,内存资源的分配,系统变量的初始化等。 CS7410本身除了是Mp3/WMA的解码器,同时也是系统主控CPU,方案中不再需要MCU。  [2003-8-21 11:27:46]
[问:ecnanjing_EBY7E] EP73xx Product line 能否支持任意存储格式,比如说可以把MP3当作移动硬盘? 
[答:Mark] The EP73xx is a very powerful general purpose solution that has been very successful in many audio and other products.  Cirrus has HDD based applications already implemented on this device.  [2003-8-21 11:28:09]
[问:ken999] AM在CPU 4MHZ以上都会有干扰?cs7410最低运行频率多少Mhz? 
[答:Michael] 当系统工作在Tuner状态时,CS7410的主工作频率可以大大降低,完全可以调整至 4MHz 以下.  [2003-8-21 11:29:22]
[问:ecnanjing_EBY7E] 在MP3播放器中Flasah选 NOR和 NAND,哪个性价比更好? 
[答:Michael] 开发Flash based MP3 player,建议程序代码用NOR来存储,音乐数据用NAND来存储。  [2003-8-21 11:31:16]
[问:ken999] cs7410外部的晶震最低可以用多少?不考虑做mp3 decoder? 
[答:Michael] 没有限制,由您的应用来决定.  [2003-8-21 11:33:02]
[问:cssun] cs7410的microprocessor是51吗? 
[答:Michael] 不是。是32位的RISC CPU.  [2003-8-21 11:33:33]
[问:ken999] 请问夏先生,cs7410是否考虑进一步支持ogg、mpc 、aac、decoder? 
[答:Mark] There are many varieties of audio codecs available.  The primary driver behind coding formats that have become popular has been the availability of content.  Currently there is much content available in MP3 and increasingly in WMA, hence these formats are popolar for players.  AAC has increasing content available for paid downloads.  Ogg is used only by a small number of people for their private content and we have yet to see whether this will become a mainstream compressed audio format.  [2003-8-21 11:33:38]
[问:ecnanjing_EBY7E] 在传统的音响设计中,电源和地的走线对音质有很大影响。在MP3这样的数字音响中要注意些什么?谢谢! 
[答:Larry] Important things to watch out for include:1. Trace length of high-frequency signal (such as CPU and audio clock) need to be short2. Mute circuit to avoid power-up "pop" noise3. Good ground plane around the servo subsystem4. Isolate your analog and digital suppliesThere may be others....  [2003-8-21 11:34:48]
[问:kello] 可否提供详细的音频测试方法指引? 
[答:Michael] 请参见我们的 Presentation.  [2003-8-21 11:34:51]
[问:ljp] 能否告诉CD播放器的请单(BOM)成本? 
[答:Mark] Please contact our sales representatives to have a detailed discussion on the different types of CD-MP3 player platforms available and their different BOM costs.  Go to www.cirrus.com for more information.  [2003-8-21 11:35:14]
[问:qin] MP3中的DAC应有多少为才能达到要求? 
[答:Larry] 16-bit is usually a good bet.  [2003-8-21 11:36:25]
[问:lixb] DVDAudio在便携式产品中的发展前景怎么样?Cirrus Logic有没有支持DVDAudio的芯片? 
[答:Mark] The DVD audio forum has approved the use of dual layer discs the same as for SACD discs.  These Dual layer discs willl already play in CS7410 based CD-MP3 players.  [2003-8-21 11:36:38]
[问:huayun] 网上有解码芯片的资料吗? 
[答:Peter] please visit www.cirrus.com for detailed information. thank you.  [2003-8-21 11:38:56]
[问:ken999] 贵公司认为cs7410的前景如何? 
[答:Mark] The CS7410 is an increasingly popular solution for CD-MP3 players as our customers understand the need for an excellent UI, full application coverage, and ease of programability.  [2003-8-21 11:39:59]
[问:quzhe] mp3的编码规则? 
[答:Larry] MP3 encoding is a complex algorithm that take into human psychoacoustic model and mask out frequency range not important to human audio perception.  The residual bands are compressed according to allocate bit rate.  [2003-8-21 11:40:14]
[问:hongmao] 请问:贵公司提供的MP3方案,是否可以直接录制声音-〉MP3 并存储于FLASH? 
[答:Michael] CS7410参考方案目前不支持。但Cirrus EPP73XX/93XX 可以支持该功能。  [2003-8-21 11:40:31]
[问:ken999] cs7410的用户需要交wma的liesece吗?还是工厂自己交? 
[答:Mark] You must contact Microsoft for details of their licensing policies.  Cirrus will help our customers to contact Microsoft to obtain the answers that they need.  [2003-8-21 11:41:30]
[问:kello] 在很多音频设计领域,实际遇到的一个重要问题是客观的音频测试指标并不能有完全相同的主观评价效果,如何在音响系统或者便携式高品质音频中使用正确的测试方法得到统一? 
[答:Michael] 个人认为,先要通过主观听音测试,然后才是客观指标测试。如果听起来都感觉不好,就算指标通过了,意义也不大.  [2003-8-21 11:42:30]
[问:songwt] 希望能下载参考设计的图纸。 
[答:Michael] 请联系Cirrus 销售代表  [2003-8-21 11:43:11]
[问:samking] 防震90秒,读碟防震45秒,做MP3方案采用何种芯片比较合? 
[答:Michael] CS7410, EPP73XX/EPP93XX 系列产品都能达到ESP时间的上述要求。  [2003-8-21 11:44:47]
[问:ken999] ess3890w只是需要多一个audio DAC,如果用的servo带的话,比如sony 3059的话。那整个project的IC就一样,BOM cost 应该远远低与cs7410的,而ess3890w现在的价格是$1.5,cs7410了?请问贵公司认为cs7410的前景如何? 
[答:Mark] CS7410 based solutions have both good power consumption and low BOM cost due to the level of system integration and the core technology used.  [2003-8-21 11:45:18]
[问:kello] 音频测试方法?persentation----请告知下载URL可以吗? 
[答:Michael] 请到 chinaecnet 下载  [2003-8-21 11:45:37]
[问:chinagreatman] CS7410开发系统中的DSP提供什么算法接口? 
[答:Michael] 通过API调用DSP库  [2003-8-21 11:46:34]
[问:lijianguo] 我公司有意开发利用CIRRUS的CS7410解码器的MP3播放器,请问应选用哪一款的CIRRUS开发平台? 
[答:Mark] Cirrus has both development and reference platforms available.  The development platform makes it easy to add extra features to the solution.  The reference platforms can also be used as development platforms, but are more specific in their capabilities.  For more information on the development and reference platforms that are available please contact Cirrus Logic sales representatives.  [2003-8-21 11:48:05]
[问:hgc4480] 请问如何判断MP3声音的质量?怎样测试MP3的信噪比(S/N)?谢谢! 
[答:Larry] To test CDDA audio, you can test audio quality, such as SNR, by using a 0dB test tone CD (usually @ 1kHz) and monitor the output using an audio analyzer (e.g., Audio Precision).  SNR is the dB measure between the tone peak and the noise floor.To also consider quality loss due to MP3, you will need to compare the original audio with the decoded audio.  The audio should be a frequency sweep from 22Hz to 22kHz.  compare the two sweeps will give you a good indication of the MP3 quality loss.  You can also compare the THD differences.  [2003-8-21 11:48:05]
[问:32kmcu] 贵司有无评估板? 
[答:Michael] 有集评估和开发功能为一体的演示板。请联系Cirrus 的销售代表。  [2003-8-21 11:48:33]
[问:ponywang] Cirrus可以release源代码和仿真调试工具给客户吗?需要签什么协议? 
[答:Michael] 可以。请联系Cirrus的销售代表。  [2003-8-21 11:48:54]
[问:szawang] MP3\WMA 的文件头、数据格式的资料在何处找到? 
[答:Larry] There are public domain MP3 decoder (mad decoder) solution, but you may still need to pay a royalty.  You can get WMA only from Microsoft.  [2003-8-21 11:50:57]
[问:a2go] 请问智能手机的出现,CD/MP3/WMA便携式播放机的发展前景如何,贵公司如何降低成本? 
[答:Mark] In all product areas different people have different desires and requirements.  For some people having an MP3 player in the mobile phone will be appropriate.  There will be other people, however, who want an MP3 player that is made only for that purpose, and that is easy to use.  [2003-8-21 11:53:27]
[问:故都烟尘] 请问您觉得当前CD/MP3/WMA便携式播放机设计中最难解决的技术问题是什么?谢谢! 
[答:Larry] The most difficult technical problems for portable CD/MP3/WMA players include:- Power consumption and battery life- Disc readability- Audio quality (interference, etc.)- Anti-shock feature with very little RAM  [2003-8-21 11:54:00]
[问:tonyzhou] What OS do you use in this solution? 
[答:Larry] The design does not require an OS, but is capable of working with one.  [2003-8-21 11:55:09]
[问:chinagreatman] How to add a USB interface, if i use CS7410? Do Cirrus have plan to add USB module in the chip 
[答:Mark] Cirrus is always reviewing the requirements for new products and works to ensure that the interfaces available are appropriate to the product space that the solution is targetted for.  [2003-8-21 11:55:31]
[问:jys] How do a audio code set working in a cd/mp3/wma player? 
[答:Larry] The major software components in a cd/mp3/wma player include:- main control loop- user interface- servo control code- file system- codec (cdda/mp3/wma/adpcm)- electronic shock protection- audio post processing (e.g., EQ)  [2003-8-21 11:57:36]
[问:bill.he] Do cirrus provide total solution? 
[答:Mark] Yes.  Cirrus has complete application SW and reference designs available for CD-MP3 player solutions.  [2003-8-21 11:58:01]
[问:老虎] 请问一下贵公司的提供芯片中有音频特效处理的功能吗?如均衡等。 
[答:Larry] CS7410 has a 32-bit RISC core + a 16-bit DSP core.  The DSP core can be used for EQ.  [2003-8-21 11:58:33]
[问:chinagreatman] What kind of Algorithm supported by CS7410 DSP. 
[答:Larry] CDDA/MP3/WMA/ADPCM  [2003-8-21 11:59:21]
[问:tonyzhou] What"s the price of this solution? what need to be developed as expected by us after buy it? 
[答:Mark] Cirrus provides complete reference designs and SW for a number of CD-MP3 player solutions.  The cost of the solution depends on the specific features selected for the player.  The customer development effort is related to whether or not the customer wishes to add special features, or is happy with the standard reference designs.  For more information on our reference designs please contact a Cirrus sales representative.  [2003-8-21 12:00:19]
[问:ken999] ARM核的CPU 34Mhz可以decoder mp3,cs7410可以在多少Mhz decodermp3? 
[答:Larry] Around 28Mhz.  [2003-8-21 12:00:39]
[问:chinagreatman] The CS7410 address capable?How many Mbit memory?How about if i add a Flash Disk Function,.... need USB? 
[答:Larry] 64Mbit memory (8MB)Flash disk is possible  [2003-8-21 12:01:46]
[问:afeng] 与SUNPLUS的SPCA756比较有什么优缺点? 
[答:Mark] As well as being a low power and low cost solution the CS7410 also has complete support for WMA.  [2003-8-21 12:01:59]
[问:ponywang] 你认为CS7410用来做CAR AUDIO适合吗?抗干扰性能如何? 
[答:Michael] CAR AUDIO 是CS7410的理想应用之一。CS7410抗干扰性能已经在实践中得到验证。  [2003-8-21 12:02:33]
[问:heartofdra] 程序设计的大体框架是怎样的? 
[答:Michael] RTOS驱动下的多任务结构。  [2003-8-21 12:03:04]
[问:leefine-jn] 使用该芯片完成的系统,最小体积可达? 
[答:Mark] Cirrus reference designs are available for slimline CD-MP3 players.  [2003-8-21 12:04:11]
[问:airhog] Would you pls introduce power management in the portable design? 
[答:Larry] Power management is important in portable design and CS7410 platform solution supports the following:1. CPU clock control2. Peripheral clock control3. LCD backlight on/off4. Servo subsystem on/off  [2003-8-21 12:04:39]