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学以致用---博主简介:专注语音、视频数字信号处理方面的研究以及算法在手机平台上面的移植和优化。涉及语音/音频编解码,语音增强,语音识别,语音音质客观评估,VOIP语音引擎 Qos算法模块和声音变速不变调和变调不变速等功能实现。熟悉ARM 各个系列的CPU,用ARMv4,ARMv5,ARMv6 and Cortex Neon 汇编优化相关算法代码,争取perforamance 最优。目前主要Windows mobile and Android platform上做相关speech/audio算法以及应用开发, HEVC 编解码器PC 和手机上的开发与应用。(交流Email:liupin.2008@gmail.com)

Network Protocols

The following network protocols are supported for audio and video playback:

  • RTSP (RTP, SDP)
  • HTTP/HTTPS progressive streaming
  • HTTP/HTTPS live streaming draft protocol:
    • MPEG-2 TS media files only
    • Protocol version 3 (Android 4.0 and above)
    • Protocol version 2 (Android 3.x)
    • Not supported before Android 3.0

Note: HTTPS is not supported before Android 3.1.

Core Media Formats

The table below describes the media format support built into the Android platform. Note that any given mobile device may provide support for additional formats or file types not listed in the table.

Note: Media codecs that are not guaranteed to be available on all Android platform versions are accordingly noted in parentheses—for example "(Android 3.0+)".

Table 1. Core media format and codec support.

TypeFormat / CodecEncoderDecoderDetailsSupported File Type(s) / Container Formats
Audio AAC LC/LTP Mono/Stereo content in any combination of standard bit rates up to 160 kbps and sampling rates from 8 to 48kHz • 3GPP (.3gp) • MPEG-4 (.mp4, .m4a) • ADTS raw AAC (.aac, decode in Android 3.1+, encode in Android 4.0+, ADIF not supported) • MPEG-TS (.ts, not seekable, Android 3.0+)
HE-AACv1 (AAC+)  
HE-AACv2 (enhanced AAC+)  
AMR-NB 4.75 to 12.2 kbps sampled @ 8kHz   3GPP (.3gp)
AMR-WB 9 rates from 6.60 kbit/s to 23.85 kbit/s sampled @ 16kHz   3GPP (.3gp)
FLAC   (Android 3.1+) Mono/Stereo (no multichannel). Sample rates up to 48 kHz (but up to 44.1 kHz is recommended on devices with 44.1 kHz output, as the 48 to 44.1 kHz downsampler does not include a low-pass filter). 16-bit recommended; no dither applied for 24-bit.   FLAC (.flac) only
MP3   Mono/Stereo 8-320Kbps constant (CBR) or variable bit-rate (VBR)   MP3 (.mp3)
MIDI   MIDI Type 0 and 1. DLS Version 1 and 2. XMF and Mobile XMF. Support for ringtone formats RTTTL/RTX, OTA, and iMelody • Type 0 and 1 (.mid, .xmf, .mxmf) • RTTTL/RTX (.rtttl, .rtx) • OTA (.ota) • iMelody (.imy)
Vorbis     • Ogg (.ogg) • Matroska (.mkv, Android 4.0+)
PCM/WAVE   8- and 16-bit linear PCM (rates up to limit of hardware)   WAVE (.wav)
Image JPEG Base+progressive   JPEG (.jpg)
GIF     GIF (.gif)
PNG   PNG (.png)
BMP     BMP (.bmp)
WEBP (Android 4.0+) (Android 4.0+)     WebP (.webp)
Video H.263   • 3GPP (.3gp) • MPEG-4 (.mp4)
H.264 AVC (Android 3.0+) Baseline Profile (BP) • 3GPP (.3gp) • MPEG-4 (.mp4) • MPEG-TS (.ts, AAC audio only, not seekable, Android 3.0+)
MPEG-4 SP     3GPP (.3gp)
VP8   (Android 2.3.3+) Streamable only in Android 4.0 and above WebM (.webm) • Matroska (.mkv, Android 4.0+)

Video Encoding Recommendations

Table 2, below, lists examples of video encoding profiles and parameters that the Android media framework supports for playback. In addition to these encoding parameter recommendations, a device's available video recording profiles can be used as a proxy for media playback capabilities. These profiles can be inspected using the CamcorderProfile class, which is available since API level 8.

Table 2. Examples of supported video encoding parameters.

 SD (Low quality)SD (High quality)HD (Not available on all devices)
Video codec H.264 Baseline Profile H.264 Baseline Profile H.264 Baseline Profile
Video resolution 176 x 144 px 480 x 360 px 1280 x 720 px
Video frame rate 12 fps 30 fps 30 fps
Video bitrate 56 Kbps 500 Kbps 2 Mbps
Audio codec AAC-LC AAC-LC AAC-LC
Audio channels 1 (mono) 2 (stereo) 2 (stereo)
Audio bitrate 24 Kbps 128 Kbps 192 Kbps

For video content that is streamed over HTTP or RTSP, there are additional requirements:

  • For 3GPP and MPEG-4 containers, the moov atom must precede any mdat atoms, but must succeed the      ftyp atom.
  • For 3GPP, MPEG-4, and WebM containers, audio and video samples corresponding to the same time offset may be no more than 500 KB apart.      To minimize this audio/video drift, consider interleaving audio and video in smaller chunk sizes.

linking: http://developer.android.com/guide/appendix/media-formats.html

 

posted on 2012-06-13 23:10  liupin  阅读(1297)  评论(0)    收藏  举报

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