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      1 /*
      2 **
      3 ** Copyright 2007, The Android Open Source Project
      4 **
      5 ** Licensed under the Apache License, Version 2.0 (the "License");
      6 ** you may not use this file except in compliance with the License.
      7 ** You may obtain a copy of the License at
      8 **
      9 **     http://www.apache.org/licenses/LICENSE-2.0
     10 **
     11 ** Unless required by applicable law or agreed to in writing, software
     12 ** distributed under the License is distributed on an "AS IS" BASIS,
     13 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     14 ** See the License for the specific language governing permissions and
     15 ** limitations under the License.
     16 */
     17 
     18 #define LOG_TAG "AmrInputStream"
     19 #include "utils/Log.h"
     20 
     21 #include "jni.h"
     22 #include "JNIHelp.h"
     23 #include "android_runtime/AndroidRuntime.h"
     24 #include "gsmamr_enc.h"
     25 
     26 // ----------------------------------------------------------------------------
     27 
     28 using namespace android;
     29 
     30 // Corresponds to max bit rate of 12.2 kbps.
     31 static const int MAX_OUTPUT_BUFFER_SIZE = 32;
     32 static const int FRAME_DURATION_MS = 20;
     33 static const int SAMPLING_RATE_HZ = 8000;
     34 static const int SAMPLES_PER_FRAME = ((SAMPLING_RATE_HZ * FRAME_DURATION_MS) / 1000);
     35 static const int BYTES_PER_SAMPLE = 2;  // Assume 16-bit PCM samples
     36 static const int BYTES_PER_FRAME = (SAMPLES_PER_FRAME * BYTES_PER_SAMPLE);
     37 
     38 struct GsmAmrEncoderState {
     39     GsmAmrEncoderState()
     40         : mEncState(NULL),
     41           mSidState(NULL),
     42           mLastModeUsed(0) {
     43     }
     44 
     45     ~GsmAmrEncoderState() {}
     46 
     47     void*   mEncState;
     48     void*   mSidState;
     49     int32_t mLastModeUsed;
     50 };
     51 
     52 static jint android_media_AmrInputStream_GsmAmrEncoderNew
     53         (JNIEnv *env, jclass clazz) {
     54     GsmAmrEncoderState* gae = new GsmAmrEncoderState();
     55     if (gae == NULL) {
     56         jniThrowRuntimeException(env, "Out of memory");
     57     }
     58     return (jint)gae;
     59 }
     60 
     61 static void android_media_AmrInputStream_GsmAmrEncoderInitialize
     62         (JNIEnv *env, jclass clazz, jint gae) {
     63     GsmAmrEncoderState *state = (GsmAmrEncoderState *) gae;
     64     int32_t nResult = AMREncodeInit(&state->mEncState, &state->mSidState, false);
     65     if (nResult != OK) {
     66         jniThrowExceptionFmt(env, "java/lang/IllegalArgumentException",
     67                 "GsmAmrEncoder initialization failed %d", nResult);
     68     }
     69 }
     70 
     71 static jint android_media_AmrInputStream_GsmAmrEncoderEncode
     72         (JNIEnv *env, jclass clazz,
     73          jint gae, jbyteArray pcm, jint pcmOffset, jbyteArray amr, jint amrOffset) {
     74 
     75     jbyte inBuf[BYTES_PER_FRAME];
     76     jbyte outBuf[MAX_OUTPUT_BUFFER_SIZE];
     77 
     78     env->GetByteArrayRegion(pcm, pcmOffset, sizeof(inBuf), inBuf);
     79     GsmAmrEncoderState *state = (GsmAmrEncoderState *) gae;
     80     int32_t length = AMREncode(state->mEncState, state->mSidState,
     81                                 (Mode) MR122,
     82                                 (int16_t *) inBuf,
     83                                 (unsigned char *) outBuf,
     84                                 (Frame_Type_3GPP*) &state->mLastModeUsed,
     85                                 AMR_TX_WMF);
     86     if (length < 0) {
     87         jniThrowExceptionFmt(env, "java/io/IOException",
     88                 "Failed to encode a frame with error code: %d", length);
     89         return -1;
     90     }
     91 
     92     // The 1st byte of PV AMR frames are WMF (Wireless Multimedia Forum)
     93     // bitpacked, i.e.;
     94     //    [P(4) + FT(4)]. Q=1 for good frame, P=padding bit, 0
     95     // Here we are converting the header to be as specified in Section 5.3 of
     96     // RFC 3267 (AMR storage format) i.e.
     97     //    [P(1) + FT(4) + Q(1) + P(2)].
     98     if (length > 0) {
     99       outBuf[0] = (outBuf[0] << 3) | 0x4;
    100     }
    101 
    102     env->SetByteArrayRegion(amr, amrOffset, length, outBuf);
    103 
    104     return length;
    105 }
    106 
    107 static void android_media_AmrInputStream_GsmAmrEncoderCleanup
    108         (JNIEnv *env, jclass clazz, jint gae) {
    109     GsmAmrEncoderState *state = (GsmAmrEncoderState *)gae;
    110     AMREncodeExit(&state->mEncState, &state->mSidState);
    111     state->mEncState = NULL;
    112     state->mSidState = NULL;
    113 }
    114 
    115 static void android_media_AmrInputStream_GsmAmrEncoderDelete
    116         (JNIEnv *env, jclass clazz, jint gae) {
    117     delete (GsmAmrEncoderState*)gae;
    118 }
    119 
    120 // ----------------------------------------------------------------------------
    121 
    122 static JNINativeMethod gMethods[] = {
    123     {"GsmAmrEncoderNew",        "()I",        (void*)android_media_AmrInputStream_GsmAmrEncoderNew},
    124     {"GsmAmrEncoderInitialize", "(I)V",       (void*)android_media_AmrInputStream_GsmAmrEncoderInitialize},
    125     {"GsmAmrEncoderEncode",     "(I[BI[BI)I", (void*)android_media_AmrInputStream_GsmAmrEncoderEncode},
    126     {"GsmAmrEncoderCleanup",    "(I)V",       (void*)android_media_AmrInputStream_GsmAmrEncoderCleanup},
    127     {"GsmAmrEncoderDelete",     "(I)V",       (void*)android_media_AmrInputStream_GsmAmrEncoderDelete},
    128 };
    129 
    130 
    131 int register_android_media_AmrInputStream(JNIEnv *env)
    132 {
    133     const char* const kClassPathName = "android/media/AmrInputStream";
    134 
    135     return AndroidRuntime::registerNativeMethods(env,
    136             kClassPathName, gMethods, NELEM(gMethods));
    137 }
    138