我正在尝试在android中使用ffmpeg播放音频mp3文件 但是我在下面提到的代码中遇到了问题
如何使用ffmpeg播放mp3
void JNICALL Java_com_music_MainActivity_loadFile(JNIEnv* env, jobject obj,jstring file,jbyteArray array)
{
jboolean isfilenameCopy;
const char * filename = (*env)->GetStringUTFChars(env, file, &isfilenameCopy);
AVCodec *codec;
AVCodecContext *c= NULL;
int out_size, len;
FILE *f, *outfile;
uint8_t *outbuf;
uint8_t inbuf[AUDIO_INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE];
AVPacket avpkt;
jclass cls = (*env)->GetObjectClass(env, obj);
jmethodID play = (*env)->GetMethodID(env, cls, "playSound", "([BI)V");//At the begining of your main function
av_init_packet(&avpkt);
printf("Audio decoding\n");
__android_log_print(ANDROID_LOG_INFO, DEBUG_TAG, "inside load file");
/* find the mpeg audio decoder */
codec = avcodec_find_decoder(CODEC_ID_MP3);
if (!codec) {
fprintf(stderr, "codec not found\n");
exit(1);
}
c= avcodec_alloc_context();
/* open it */
if (avcodec_open(c, codec) < 0) {
fprintf(stderr, "could not open codec\n");
exit(1);
}
__android_log_print(ANDROID_LOG_INFO, DEBUG_TAG, "open avcode");
outbuf = malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE);
__android_log_print(ANDROID_LOG_INFO, DEBUG_TAG, "open %s",outbuf);
f = fopen(filename, "rb");
if (!f) {
fprintf(stderr, "could not open %s\n", filename);
exit(1);
}
/* decode until eof */
avpkt.data = inbuf;
avpkt.size = fread(inbuf, 1, AUDIO_INBUF_SIZE, f);
__android_log_print(ANDROID_LOG_INFO, DEBUG_TAG, "data =%s and size %d",avpkt.data,avpkt.size);
while (avpkt.size > 0) {
out_size = AVCODEC_MAX_AUDIO_FRAME_SIZE;
len = avcodec_decode_audio3(c, (short *)outbuf, &out_size, &avpkt);
__android_log_print(ANDROID_LOG_INFO, DEBUG_TAG, "length =%d",len);
if (len < 0) {
fprintf(stderr, "Error while decoding\n");
__android_log_print(ANDROID_LOG_INFO, DEBUG_TAG, " failed length =%d",errno);
exit(1);
}
if (out_size > 0) {
/* if a frame has been decoded, output it */
jbyte *bytes = (*env)->GetByteArrayElements(env, array, NULL);
memcpy(bytes, outbuf, out_size); //
(*env)->ReleaseByteArrayElements(env, array, bytes, 0);
(*env)->CallVoidMethod(env, obj, play, array, out_size);
}
avpkt.size -= len;
avpkt.data += len;
if (avpkt.size < AUDIO_REFILL_THRESH) {
/* Refill the input buffer, to avoid trying to decode
* incomplete frames. Instead of this, one could also use
* a parser, or use a proper container format through
* libavformat. */
memmove(inbuf, avpkt.data, avpkt.size);
avpkt.data = inbuf;
len = fread(avpkt.data + avpkt.size, 1,
AUDIO_INBUF_SIZE - avpkt.size, f);
if (len > 0)
avpkt.size += len;
}
}
fclose(f);
free(outbuf);
avcodec_close(c);
av_free(c);
}
我在
中得到len = - 1len = avcodec_decode_audio3(c, (short *)outbuf, &out_size, &avpkt);
我做错了什么？
请帮助
答案 0 :(得分：4)
void JNICALL Java_com_music_MainActivity_loadFile(JNIEnv* env, jobject obj,jstring file,jbyteArray array)
{
jboolean isCopy;
int i;
int err;
FILE *f, *outfile;
int audioStream=-1;
int res;
int decoded = 0;
int out_size;
AVFrame *frame = av_frame_alloc();
int got_frame;
uint8_t inbuf[AUDIO_INBUF_SIZE + FF_INPUT_BUFFER_PADDING_SIZE];
jclass cls = (*env)->GetObjectClass(env, obj);
jmethodID play = (*env)->GetMethodID(env, cls, "playSound", "([BI)V");//At the begining of your main function
const char * szfile = (*env)->GetStringUTFChars(env, file, &isCopy);
LOGI("in load file");
if ((ret = avformat_open_input(&fmt_ctx, szfile, NULL, NULL)) < 0)
{
LOGE("Cannot open input file\n");
}
LOGE("file load %s\n",szfile);
if ((ret = avformat_find_stream_info(fmt_ctx, NULL)) < 0)
{
LOGE("Cannot find stream information\n");
}
/* select the audio stream */
ret = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_AUDIO, -1, -1, &dec, 0);
if (ret < 0)
{
LOGE("Cannot find a audio stream in the input file\n");
}
// timeBase = (int64_t(aCodecCtx->time_base.num) * AV_TIME_BASE) / int64_t(aCodecCtx->time_base.den);
audio_stream_index = ret;
dec_ctx = fmt_ctx->streams[audio_stream_index]->codec;
av_opt_set_int(dec_ctx, "refcounted_frames", 1, 0);
if ((ret = avcodec_open2(dec_ctx, dec, NULL)) < 0)
{
LOGE("Cannot open audio decoder\n");
}
dec_ctx->sample_fmt =AV_SAMPLE_FMT_S16
dec_ctx->codec_id = AV_CODEC_ID_AAC;
f = fopen(szfile, "rb");
if (!f)
{
LOGE("could not open");
exit(1);
}
// LOGE("time of frame %d",aCodecCtx->time_base.num);
// av_seek_frame();
// timeBase =(aCodecCtx->time_base.num *AV_TIME_BASE)/(aCodecCtx->time_base.den);
// LOGE("time of frame %d",aCodecCtx->time_base.den);
LOGE("time of frame %d",timeBase);
packet.data = inbuf;
packet.size = fread(inbuf, 1, AUDIO_INBUF_SIZE, f);
LOGE("Stage 5");
while (1)
{
if ((ret = av_read_frame(fmt_ctx, &packet)) < 0)
break;
if (packet.stream_index == audio_stream_index)
{
avcodec_get_frame_defaults(frame);
got_frame = 0;
ret = avcodec_decode_audio4(dec_ctx, frame, &got_frame, &packet);
LOGE("len=%d",ret);
if (ret < 0)
{
LOGE("Error decoding audio\n");
continue;
}
if (got_frame)
{
LOGE("begin frame decode\n");
int data_size = av_samples_get_buffer_size(NULL, dec_ctx->channels,frame->nb_samples,dec_ctx->sample_fmt, 1);
LOGE("after frame decode\n");
jbyte *bytes = (*env)->GetByteArrayElements(env, array, NULL);
memcpy(bytes, frame->data[0], data_size); //
(*env)->ReleaseByteArrayElements(env, array, bytes, 0);
(*env)->CallVoidMethod(env, obj, play, array, data_size);
}
packet.size -= ret;
packet.data += ret;
packet.pts = AV_NOPTS_VALUE;
if (packet.size < AUDIO_REFILL_THRESH)
{
memmove(inbuf, packet.data, packet.size);
packet.data = inbuf;
ret = fread(packet.data + packet.size, 1, AUDIO_INBUF_SIZE - packet.size, f);
if (ret > 0)
packet.size += ret;
}
}
}
av_free_packet(&packet);
}
试试这段代码我做了几次改变，现在工作正常
答案 1 :(得分：1)
要从MP3文件中正确读取数据包，您必须使用AVFormatContext结构。
代码看起来像这样（这段代码没有正确的完成，错误检查等）
AVFormatContext * fCtx = NULL;
if(avformat_open_input(&fCtx, filename, NULL, NULL) < 0)
exit(1);
avformat_find_stream_info(fCtx, NULL);
AVCodec * codec = nullptr;
int strm = av_find_best_stream(fCtx, AVMEDIA_TYPE_AUDIO, -1, -1, &codec, 0);
AVCodecContext codecCtx = ctx->streams[strm]->codec;
if (avcodec_open2(codecCtx, codec, nullptr) < 0)
exit(1);
for (;;)
{
AVPacket pkt;
err = av_read_frame(fCtx , &pkt);
if (AVERROR_EOF == err)
break;
if (pkt.stream_index != strm)
continue;
AVFrame frame;
int gotFrame = 0;
int len = avcodec_decode_audio4(codecCtx, &frame, &gotFrame, &pkt)
// or avcodec_decode_audio3 in previous version of ffmpeg, as it is written you.
/// check result and use frame (or buffer in case of avcodec_decode_audio3)
}