Dear All,
Thanks to @nirbheek ,
Now I’m updating architecture and testing decoding with both gstreamer and non - gstreamer applications :
I am looking forward to the day I can share this with you all.
/*
* c2l_player
* Copyright (c) 2026 Changyong Ahn <changyong.ahn@lge.com>
*/
#include <codec2-linux/codec2_linux.h>
#include <alsa/asoundlib.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
static int find_mp3_frame(const uint8_t *buf, size_t len, size_t *frame_size) {
/* MP3 sync: 0xFF 0xE0+ (11 sync bits) */
for (size_t i = 0; i + 3 < len; i++) {
if (buf[i] == 0xFF && (buf[i+1] & 0xE0) == 0xE0) {
int version = (buf[i+1] >> 3) & 3; /* 0=2.5, 2=2, 3=1 */
int layer = (buf[i+1] >> 1) & 3; /* 1=III, 2=II, 3=I */
int br_idx = (buf[i+2] >> 4) & 0xF;
int sr_idx = (buf[i+2] >> 2) & 3;
int padding = (buf[i+2] >> 1) & 1;
if (version == 1 || layer == 0 || br_idx == 0 || br_idx == 15 || sr_idx == 3)
continue;
static const int bitrates[16] = {0,32,40,48,56,64,80,96,112,128,160,192,224,256,320,0};
static const int samplerates[4] = {44100, 48000, 32000, 0};
int bitrate = bitrates[br_idx] * 1000;
int samplerate = samplerates[sr_idx];
if (version == 0) samplerate /= 4; /* MPEG 2.5 */
else if (version == 2) samplerate /= 2; /* MPEG 2 */
int fsize;
if (layer == 3) /* Layer I */
fsize = (12 * bitrate / samplerate + padding) * 4;
else /* Layer II, III */
fsize = 144 * bitrate / samplerate + padding;
if (fsize > 0 && i + fsize <= len) {
*frame_size = fsize;
return (int)i;
}
}
}
return -1;
}
int main(int argc, char *argv[]) {
if (argc < 2) {
fprintf(stderr, "Usage: %s <file.mp3> [speed]\n", argv[0]);
fprintf(stderr, " speed: 1.0=normal, 2.0=double, 0.5=half\n");
return 1;
}
float speed = (argc > 2) ? atof(argv[2]) : 1.0f;
if (speed <= 0) speed = 1.0f;
FILE *f = fopen(argv[1], "rb");
if (!f) { perror("fopen"); return 1; }
fseek(f, 0, SEEK_END);
size_t file_size = ftell(f);
fseek(f, 0, SEEK_SET);
uint8_t *file_data = malloc(file_size);
fread(file_data, 1, file_size, f);
fclose(f);
printf("Loaded %s (%zu bytes)\n", argv[1], file_size);
C2LContext *ctx = c2l_context_create();
c2l_context_set_resource_capacity(ctx, "cpu.audio", 100);
C2LSessionRequest req = {
.component_name = "c2.android.mp3.decoder",
.resource_id = "cpu.audio",
.resource_units = 1,
.priority = C2L_PRIORITY_FOREGROUND,
};
C2LSession *session = NULL;
C2LStatus st = c2l_session_create(ctx, &req, &session);
if (st != C2L_STATUS_OK) {
fprintf(stderr, "session_create failed: %s\n", c2l_status_string(st));
return 1;
}
printf("Decoder: %s\n", c2l_session_component_name(session));
c2l_session_start(session);
C2LAudioConfig config = { .sample_rate = 44100, .channels = 2 };
c2l_session_configure_audio(session, &config);
size_t pos = 0;
uint8_t *pcm_buf = NULL;
size_t pcm_total = 0;
size_t pcm_cap = 0;
int detected_rate = 0, detected_ch = 0;
int frame_count = 0;
while (pos < file_size) {
size_t frame_size = 0;
int offset = find_mp3_frame(file_data + pos, file_size - pos, &frame_size);
if (offset < 0) break;
pos += offset;
C2LInputBuffer input = {
.data = file_data + pos,
.size = frame_size,
.pts_ns = C2L_TIME_NONE,
.flags = 0,
};
c2l_session_queue(session, &input);
pos += frame_size;
frame_count++;
C2LOutputBuffer output = {0};
while (c2l_session_pull(session, &output) == C2L_STATUS_OK && output.size > 0) {
if (pcm_total + output.size > pcm_cap) {
pcm_cap = (pcm_total + output.size) * 2;
pcm_buf = realloc(pcm_buf, pcm_cap);
}
memcpy(pcm_buf + pcm_total, output.data, output.size);
pcm_total += output.size;
if (!detected_rate && output.sample_rate) {
detected_rate = output.sample_rate;
detected_ch = output.channels;
}
c2l_output_buffer_release(&output);
memset(&output, 0, sizeof(output));
}
}
c2l_session_drain(session);
C2LOutputBuffer output = {0};
while (c2l_session_pull(session, &output) == C2L_STATUS_OK && output.size > 0) {
if (pcm_total + output.size > pcm_cap) {
pcm_cap = (pcm_total + output.size) * 2;
pcm_buf = realloc(pcm_buf, pcm_cap);
}
memcpy(pcm_buf + pcm_total, output.data, output.size);
pcm_total += output.size;
if (!detected_rate && output.sample_rate) {
detected_rate = output.sample_rate;
detected_ch = output.channels;
}
c2l_output_buffer_release(&output);
memset(&output, 0, sizeof(output));
}
printf("Decoded: %d frames → %zu bytes PCM (%dHz, %dch)\n",
frame_count, pcm_total, detected_rate, detected_ch);
c2l_session_stop(session);
c2l_session_destroy(session);
c2l_context_destroy(ctx);
if (!detected_rate) detected_rate = 44100;
if (!detected_ch) detected_ch = 2;
int playback_rate = (int)(detected_rate * speed);
printf("Playing at %dx%dch @ %dHz (speed=%.1fx)\n",
16, detected_ch, playback_rate, speed);
snd_pcm_t *pcm_handle;
int err = snd_pcm_open(&pcm_handle, "default", SND_PCM_STREAM_PLAYBACK, 0);
if (err < 0) {
fprintf(stderr, "ALSA open: %s\n", snd_strerror(err));
fprintf(stderr, "Writing to /tmp/c2l_out.raw instead\n");
FILE *out = fopen("/tmp/c2l_out.raw", "wb");
fwrite(pcm_buf, 1, pcm_total, out);
fclose(out);
printf("Saved %zu bytes to /tmp/c2l_out.raw\n", pcm_total);
goto cleanup;
}
snd_pcm_set_params(pcm_handle,
SND_PCM_FORMAT_S16_LE,
SND_PCM_ACCESS_RW_INTERLEAVED,
detected_ch,
playback_rate,
1, /* allow ALSA software resampling */
500000); /* desired latency in microseconds (500ms) */
size_t frame_bytes = detected_ch * 2; /* bytes per frame (S16LE = 2 bytes/sample) */
size_t total_frames = pcm_total / frame_bytes;
snd_pcm_sframes_t written = snd_pcm_writei(pcm_handle, pcm_buf, total_frames);
if (written < 0) {
snd_pcm_recover(pcm_handle, written, 0);
written = snd_pcm_writei(pcm_handle, pcm_buf, total_frames);
}
printf("Played %ld/%zu frames\n", (long)written, total_frames);
snd_pcm_drain(pcm_handle);
snd_pcm_close(pcm_handle);
cleanup:
free(pcm_buf);
free(file_data);
printf("Done.\n");
return 0;
}
