Using Android Mediarecorder C + + class for video encoding

Source: Internet
Author: User
Tags prepare

in this case, media source is camera. (Learning platform is android sdk6.0)

Call Graph:


    1. Recorder = New Mediarecorder (String16 ());

Classmediarecorder:public Bnmediarecorderclient,

Public Virtualimediadeathnotifier

    1. When we create the Mediarecorder, we get the Imediaplayerservice pointer before we create the Imediarecorder

( declaration of sp<imediarecorder> Mmediarecorder;)

Mmediarecorder =service->createmediarecorder (oppackagename);

    1. in Service->createmediarecorder, the object is imediaplayerservice sequence session (using data packaging), and then the request Create_media_recorder sent to remote(that is , bpbinder) processing

Remote ()->transact (Create_media_recorder, data,&reply);

    1. Finally, the local corresponding object is created according to the remote reply.

Interface_cast<imediarecorder> (Reply.readstrongbinder ());

    1. The following methods are passed Bpmediarecorder(remote) to send to the bnmediarecorder operation.

    2. A) bnmediarecorder inherited the bninterface<imediarecorder>and realized the ontransact

Classbnmediarecorder: publicbninterface<imediarecorder>



Virtual status_t ontransact (uint32_t code,

constparcel& data,


uint32_tflags = 0);


    1. in this method , each operation has a corresponding processing branch

    2. c) is a virtual function, Specific work by mediarecorderclient to complete: mediarecorderclient:public bnmediarecorder

    3. Class Bpmediarecorder: public Bpinterface<imediarecorder>

in the corresponding method, the last is passed Remote Give Bn processing, such as:

Parceldata, reply;

Data.writeinterfacetoken (Imediarecorder::getinterfacedescriptor ());

Data.writestring8 (params);

Remote ()->transact (Set_parameters,data, &reply);

    1. Recorder->setparameters (...)

    2. Recorder->prepare ()

    3. Recorder->start ()

    4. 3. the Mediarecorderbase class is encapsulated in mediarecorderclient , and each task has to be completed

in the you can see in the Mediarecorderclient constructor

Mrecorder = Avmediaservicefactory::get (),createstagefrightrecorder(oppackagename);

    1. Therefore, the specific work is done by Stagefrightrecorder to finish.

    2. in the in AVMediaServiceFactory.cpp

Stagefrightrecorder*avmediaservicefactory::createstagefrightrecorder (

Const STRING16 &oppackagename) {

Return Newstagefrightrecorder (Oppackagename);


    1. Stagefrightrecorder Recorder->start()

Call Stagefrightrecorder in prepare or start::p repareinternal ()

In this case, according to the output encoding settings, select the corresponding encoder to initialize.

us to Output_format_mpeg_4 As an example for analysis

Enter setupmpeg4orwebmrecording () according to the output format

    1. Setupmpeg4orwebmrecording ()

Here you create a Mpeg4writer

    1. writer = Mp4writer =avfactory::get ()->creatempeg4writer (MOUTPUTFD);

    2. Setupmediasource specifying the camera as the input source for encoder

    3. Sp<mediasource> encoder;

Err = Setupvideoencoder (MediaSource, &encoder); Create Encoder

    1. Setupvideoencoder (Mediasource,&encoder);

first , the various parameter settings in the camera are read out and set into the encoder (The default value is used for camera null )

Sp<metadata>meta = Camerasource->getformat ();

int32_t width, height, stride,sliceheight, ColorFormat;

CHECK (Meta->findint32 (kkeywidth,&width));

CHECK (Meta->findint32 (kkeyheight,&height));

CHECK (Meta->findint32 (kkeystride,&stride));

CHECK (Meta->findint32 (Kkeysliceheight, &sliceheight));

CHECK (Meta->findint32 (Kkeycolorformat, &colorformat));

Format->setint32 ("width", width);

Format->setint32 ("height", height);

Format->setint32 ("Stride", stride);

Format->setint32 ("Slice-height", sliceheight);

Format->setint32 ("Color-format", ColorFormat);

The custom parameter setting functionis reserved here , which is not implemented by default in Android, is an empty function

then create the encoder.

Sp<mediacodecsource> Encoder =mediacodecsource::create (

Mlooper, format, camerasource,mpersistentsurface, flags);

    1. Sp<mediacodecsource> Encoder

=mediacodecsource::create (





    1. ;

in the create function , start with a new object,

Sp<mediacodecsource> MediaSource =

New Mediacodecsource (looper, format, source, consumer, flags);

if (mediasource->init () = = OK) {

return mediaSource;


    1. Mediacodecsource::init ()

status_t err = Initencoder ();

    1. Initencoder (){

Mreflector = new Ahandlerreflector<mediacodecsource> (this);

Mlooper->registerhandler (Mreflector);

Mcodeclooper = new Alooper;

Mcodeclooper->setname ("Codec_looper");

Mcodeclooper->start ();


MEncoder =mediacodec::createbytype (

Mcodeclooper,outputmime.c_str (), TRUE/* encoder */);


Mencoderactivitynotify =new amessage (kwhatencoderactivity, mreflector);

Mencoder->setcallback (mencoderactivitynotify);

status_t Err =mencoder->configure (


NULL/*nativewindow */,

NULL/* crypto*/,



Err = Mencoder->start ();

    1. Mediacodec::createbytype (

Mcodeclooper, Outputmime.c_str (), TRUE/* Encoder */) {

Sp<mediacodec> codec = new Mediacodec (looper, PID);

Const STATUS_TRET = Codec->init (MIME, True/* Nameistype */, encoder);


    1. Mediacodec::init (const astring&name, BOOL Nameistype, BOOL encoder) {


Name contains video, Nameistype is True


Mcodec =avfactory::get ()->createacodec ();


Misvideo =true;


Mcodeclooper->registerhandler (MCODEC);

Mcodec->setnotificationmessage (Newamessage (kwhatcodecnotify, this));

sp<amessage> msg = Newamessage (Kwhatinit, this);

Msg->setstring ("name", name);

Msg->setint32 ("Nameistype", Nameistype);

if (Nameistype) {

Msg->setint32 ("encoder", encoder);


status_t err;

vector<mediaresource> resources;

const char *type = Securecodec? Kresourcesecurecodec:kresourcenonsecurecodec;

const char *subtype = misvideo? Kresourcevideocodec:kresourceaudiocodec;

Resources.push_back (Mediaresource (String8 (type), String8 (subtype), 1));

for (int i = 0; I <= kmaxretry; ++i) {

if (i > 0) {

Don ' t try to reclaim resourcefor the first time.

if (!mresourcemanagerservice->reclaimresource (resources)) {




sp<amessage> response;

Err = Postandawaitresponse (msg,&response);

if (!isresourceerror (err)) {





This article is from the "Dragon Dance" blog, please be sure to keep this source

Using Android Mediarecorder C + + class for video encoding

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