add gapless

run-fb.sh

@@ -1,2 +0,0 @@
-export LIBGL_ALWAYS_SOFTWARE=1
-python3 app.py

run.sh

@@ -0,0 +1,3 @@
+#!/usr/bin/env bash
+
+exec bin/player music/pink\ floyd/dark\ side\ of\ the\ moon/01\ Speak\ to\ Me.flac music/pink\ floyd/dark\ side\ of\ the\ moon/02\ Breathe\ \(In\ the\ Air\).flac

src/main.c

@@ -1,5 +1,4 @@
-// player.c
+#include <stdint.h>
-#include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -14,166 +13,165 @@
 #define OUT_RATE 48000
 #define OUT_CHANNELS 2
 #define OUT_FORMAT AV_SAMPLE_FMT_S16
-#define OUT_LAYOUT AV_CH_LAYOUT_STEREO
+#define PRELOAD_SEC 10
 
-int main(int argc, char **argv) {
+typedef struct {
-  if (argc != 2) {
+  AVFormatContext *fmt;
-    fprintf(stderr, "usage: %s <audio-file>\n", argv[0]);
+  AVCodecContext *dec;
-    return 1;
+  SwrContext *swr;
-  }
+  AVPacket *pkt;
+  AVFrame *frm;
+  int stream;
+  int64_t duration_samples;
+  int64_t played_samples;
+  int eof;
+} Decoder;
 
-  const char *filename = argv[1];
+/* ---------- Decoder helpers ---------- */
 
-  /* ---------- Open input ---------- */
+static int decoder_open(Decoder *d, const char *path) {
+  memset(d, 0, sizeof(*d));
 
-  AVFormatContext *fmt = NULL;
+  if (avformat_open_input(&d->fmt, path, NULL, NULL) < 0)
-  if (avformat_open_input(&fmt, filename, NULL, NULL) < 0) {
+    return -1;
-    fprintf(stderr, "failed to open input\n");
-    return 1;
-  }
 
-  if (avformat_find_stream_info(fmt, NULL) < 0) {
+  avformat_find_stream_info(d->fmt, NULL);
-    fprintf(stderr, "failed to read stream info\n");
-    return 1;
-  }
 
-  /* ---------- Find audio stream ---------- */
+  for (unsigned i = 0; i < d->fmt->nb_streams; i++) {
-
+    if (d->fmt->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
-  int stream_index = -1;
+      d->stream = i;
-  for (unsigned i = 0; i < fmt->nb_streams; i++) {
-    if (fmt->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
-      stream_index = i;
       break;
     }
   }
 
-  if (stream_index < 0) {
+  AVStream *s = d->fmt->streams[d->stream];
-    fprintf(stderr, "no audio stream found\n");
+  const AVCodec *codec = avcodec_find_decoder(s->codecpar->codec_id);
-    return 1;
-  }
 
-  AVStream *stream = fmt->streams[stream_index];
+  d->dec = avcodec_alloc_context3(codec);
+  avcodec_parameters_to_context(d->dec, s->codecpar);
+  avcodec_open2(d->dec, codec, NULL);
 
-  /* ---------- Decoder ---------- */
+  d->swr = swr_alloc();
+  AVChannelLayout out = AV_CHANNEL_LAYOUT_STEREO;
 
-  const AVCodec *codec = avcodec_find_decoder(stream->codecpar->codec_id);
+  av_opt_set_chlayout(d->swr, "out_chlayout", &out, 0);
-  if (!codec) {
+  av_opt_set_int(d->swr, "out_sample_rate", OUT_RATE, 0);
-    fprintf(stderr, "decoder not found\n");
+  av_opt_set_sample_fmt(d->swr, "out_sample_fmt", OUT_FORMAT, 0);
-    return 1;
-  }
 
-  AVCodecContext *dec = avcodec_alloc_context3(codec);
+  av_opt_set_chlayout(d->swr, "in_chlayout", &d->dec->ch_layout, 0);
-  avcodec_parameters_to_context(dec, stream->codecpar);
+  av_opt_set_int(d->swr, "in_sample_rate", d->dec->sample_rate, 0);
+  av_opt_set_sample_fmt(d->swr, "in_sample_fmt", d->dec->sample_fmt, 0);
 
-  if (avcodec_open2(dec, codec, NULL) < 0) {
+  swr_init(d->swr);
-    fprintf(stderr, "failed to open decoder\n");
-    return 1;
-  }
 
-  /* ---------- Resampler ---------- */
+  if (s->duration != AV_NOPTS_VALUE)
+    d->duration_samples =
+        av_rescale_q(s->duration, s->time_base, (AVRational){1, OUT_RATE});
 
-  SwrContext *swr = swr_alloc();
+  d->pkt = av_packet_alloc();
-  if (!swr) {
+  d->frm = av_frame_alloc();
-    fprintf(stderr, "failed to alloc swr\n");
-    return 1;
-  }
-
-  AVChannelLayout out_ch_layout;
-  av_channel_layout_default(&out_ch_layout, OUT_CHANNELS);
-
-  av_opt_set_chlayout(swr, "out_chlayout", &out_ch_layout, 0);
-  av_opt_set_int(swr, "out_sample_rate", OUT_RATE, 0);
-  av_opt_set_sample_fmt(swr, "out_sample_fmt", OUT_FORMAT, 0);
-
-  av_opt_set_chlayout(swr, "in_chlayout", &dec->ch_layout, 0);
-  av_opt_set_int(swr, "in_sample_rate", dec->sample_rate, 0);
-  av_opt_set_sample_fmt(swr, "in_sample_fmt", dec->sample_fmt, 0);
-
-  if (swr_init(swr) < 0) {
-    fprintf(stderr, "failed to init swr\n");
-    return 1;
-  }
-
-  if (!swr || swr_init(swr) < 0) {
-    fprintf(stderr, "failed to init resampler\n");
-    return 1;
-  }
-
-  /* ---------- ALSA ---------- */
-
-  snd_pcm_t *pcm;
-  if (snd_pcm_open(&pcm, "default", SND_PCM_STREAM_PLAYBACK, 0) < 0) {
-    fprintf(stderr, "failed to open ALSA device\n");
-    return 1;
-  }
-
-  snd_pcm_set_params(pcm, SND_PCM_FORMAT_S16_LE, SND_PCM_ACCESS_RW_INTERLEAVED,
-                     OUT_CHANNELS, OUT_RATE, 1,
-                     500000 // 0.5s latency
-  );
-
-  /* ---------- Buffers ---------- */
-
-  AVPacket *pkt = av_packet_alloc();
-  AVFrame *frm = av_frame_alloc();
-
-  uint8_t *outbuf = NULL;
-  int out_linesize = 0;
-  int max_samples = 0;
-
-  /* ---------- Decode loop ---------- */
-
-  while (av_read_frame(fmt, pkt) >= 0) {
-    if (pkt->stream_index != stream_index) {
-      av_packet_unref(pkt);
-      continue;
-    }
-
-    avcodec_send_packet(dec, pkt);
-
-    while (avcodec_receive_frame(dec, frm) == 0) {
-      int needed =
-          av_rescale_rnd(swr_get_delay(swr, dec->sample_rate) + frm->nb_samples,
-                         OUT_RATE, dec->sample_rate, AV_ROUND_UP);
-
-      if (needed > max_samples) {
-        av_freep(&outbuf);
-        av_samples_alloc(&outbuf, &out_linesize, OUT_CHANNELS, needed,
-                         OUT_FORMAT, 1);
-        max_samples = needed;
-      }
-
-      int samples = swr_convert(swr, &outbuf, needed,
-                                (const uint8_t **)frm->data, frm->nb_samples);
-
-      int written = snd_pcm_writei(pcm, outbuf, samples);
-      if (written < 0)
-        snd_pcm_recover(pcm, written, 1);
-    }
-
-    av_packet_unref(pkt);
-  }
-
-  /* ---------- Flush ---------- */
-
-  avcodec_send_packet(dec, NULL);
-  while (avcodec_receive_frame(dec, frm) == 0) {
-    int samples = swr_convert(swr, &outbuf, max_samples,
-                              (const uint8_t **)frm->data, frm->nb_samples);
-    snd_pcm_writei(pcm, outbuf, samples);
-  }
-
-  snd_pcm_drain(pcm);
-
-  /* ---------- Cleanup ---------- */
-
-  av_freep(&outbuf);
-  av_frame_free(&frm);
-  av_packet_free(&pkt);
-  swr_free(&swr);
-  avcodec_free_context(&dec);
-  avformat_close_input(&fmt);
-  snd_pcm_close(pcm);
 
   return 0;
 }
+
+static void decoder_close(Decoder *d) {
+  if (!d)
+    return;
+  av_packet_free(&d->pkt);
+  av_frame_free(&d->frm);
+  swr_free(&d->swr);
+  avcodec_free_context(&d->dec);
+  avformat_close_input(&d->fmt);
+}
+
+/* ---------- Decode PCM ---------- */
+
+static int decode_pcm(Decoder *d, uint8_t **out, int max_samples) {
+  while (1) {
+    if (!d->eof) {
+      if (av_read_frame(d->fmt, d->pkt) < 0) {
+        avcodec_send_packet(d->dec, NULL);
+        d->eof = 1;
+      } else if (d->pkt->stream_index == d->stream) {
+        avcodec_send_packet(d->dec, d->pkt);
+      }
+      av_packet_unref(d->pkt);
+    }
+
+    if (avcodec_receive_frame(d->dec, d->frm) == 0) {
+      int samples =
+          swr_convert(d->swr, out, max_samples, (const uint8_t **)d->frm->data,
+                      d->frm->nb_samples);
+      d->played_samples += samples;
+      return samples;
+    }
+
+    if (d->eof)
+      return 0;
+  }
+}
+
+/* ---------- Main ---------- */
+
+int main(int argc, char **argv) {
+  if (argc < 2) {
+    fprintf(stderr, "usage: %s track1 track2 ...\n", argv[0]);
+    return 1;
+  }
+
+  snd_pcm_t *pcm;
+  snd_pcm_open(&pcm, "default", SND_PCM_STREAM_PLAYBACK, 0);
+  snd_pcm_set_params(pcm, SND_PCM_FORMAT_S16_LE, SND_PCM_ACCESS_RW_INTERLEAVED,
+                     OUT_CHANNELS, OUT_RATE, 1, 500000);
+
+  Decoder cur = {0}, next = {0};
+  int track = 1;
+  int next_loaded = 0;
+
+  decoder_open(&cur, argv[track++]);
+
+  uint8_t *buf = NULL;
+  int linesize = 0;
+  int max_samples = OUT_RATE * 2;
+
+  av_samples_alloc(&buf, &linesize, OUT_CHANNELS, max_samples, OUT_FORMAT, 1);
+
+  while (1) {
+    int samples = decode_pcm(&cur, &buf, max_samples);
+
+    if (samples > 0) {
+      snd_pcm_writei(pcm, buf, samples);
+    }
+
+    if (!next_loaded && cur.duration_samples &&
+        cur.duration_samples - cur.played_samples < PRELOAD_SEC * OUT_RATE &&
+        track < argc) {
+      decoder_open(&next, argv[track++]);
+      next_loaded = 1;
+    }
+
+    if (samples < max_samples && cur.eof) {
+      if (next_loaded) {
+        decoder_close(&cur);
+        cur = next;
+        memset(&next, 0, sizeof(next));
+        next_loaded = 0;
+        int samples_needed = max_samples - samples;
+        samples = decode_pcm(&cur, &buf, samples_needed);
+        printf("yo read %d samples\n", samples);
+        if (samples > 0) {
+          snd_pcm_writei(pcm, buf, samples);
+        }
+        continue;
+      }
+      break;
+    }
+  }
+
+  snd_pcm_drain(pcm);
+  snd_pcm_close(pcm);
+
+  decoder_close(&cur);
+  av_freep(&buf);
+  return 0;
+}