make a test ffmpeg

Makefile

@@ -0,0 +1,28 @@
+CC      := gcc
+TARGET  := player
+SRC_DIR := src
+BUILD   := build
+
+SRCS := $(wildcard $(SRC_DIR)/*.c)
+OBJS := $(patsubst $(SRC_DIR)/%.c,$(BUILD)/%.o,$(SRCS))
+
+CFLAGS  := -Wall -Wextra -O3
+CFLAGS  += $(shell pkg-config --cflags libavformat libavcodec libavutil libswresample alsa)
+
+LDFLAGS := $(shell pkg-config --libs libavformat libavcodec libavutil libswresample alsa)
+
+all: $(TARGET)
+
+$(TARGET): $(OBJS)
+	$(CC) -o $@ $^ $(LDFLAGS)
+
+$(BUILD)/%.o: $(SRC_DIR)/%.c | $(BUILD)
+	$(CC) $(CFLAGS) -c $< -o $@
+
+$(BUILD):
+	mkdir -p $(BUILD)
+
+clean:
+	rm -rf $(BUILD) $(TARGET)
+
+.PHONY: all clean

src/main.c

@@ -1,11 +1,196 @@
-
-
+// player.c
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#include <libavformat/avformat.h>
+#include <libavcodec/avcodec.h>
+#include <libswresample/swresample.h>
+#include <libavutil/opt.h>
+
+#include <alsa/asoundlib.h>
+
+#define OUT_RATE     48000
+#define OUT_CHANNELS 2
+#define OUT_FORMAT   AV_SAMPLE_FMT_S16
+#define OUT_LAYOUT   AV_CH_LAYOUT_STEREO
+
+int main(int argc, char **argv) {
+    if (argc != 2) {
+        fprintf(stderr, "usage: %s <audio-file>\n", argv[0]);
+        return 1;
+    }
+
+    const char *filename = argv[1];
+
+    /* ---------- Open input ---------- */
+
+    AVFormatContext *fmt = NULL;
+    if (avformat_open_input(&fmt, filename, NULL, NULL) < 0) {
+        fprintf(stderr, "failed to open input\n");
+        return 1;
+    }
+
+    if (avformat_find_stream_info(fmt, NULL) < 0) {
+        fprintf(stderr, "failed to read stream info\n");
+        return 1;
+    }
+
+    /* ---------- Find audio stream ---------- */
+
+    int stream_index = -1;
+    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) {
+        fprintf(stderr, "no audio stream found\n");
+        return 1;
+    }
+
+    AVStream *stream = fmt->streams[stream_index];
+
+    /* ---------- Decoder ---------- */
+
+    AVCodec *codec =
+        avcodec_find_decoder(stream->codecpar->codec_id);
+    if (!codec) {
+        fprintf(stderr, "decoder not found\n");
+        return 1;
+    }
+
+    AVCodecContext *dec = avcodec_alloc_context3(codec);
+    avcodec_parameters_to_context(dec, stream->codecpar);
+
+    if (avcodec_open2(dec, codec, NULL) < 0) {
+        fprintf(stderr, "failed to open decoder\n");
+        return 1;
+    }
+
+    /* ---------- Resampler ---------- */
+
+    SwrContext *swr = swr_alloc_set_opts(
+        NULL,
+        OUT_LAYOUT,
+        OUT_FORMAT,
+        OUT_RATE,
+        dec->channel_layout ? dec->channel_layout
+                            : av_get_default_channel_layout(dec->channels),
+        dec->sample_fmt,
+        dec->sample_rate,
+        0,
+        NULL
+    );
+
+    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);
 
-int main() {
-    FILE *ffmpeg = popen("ffmpeg -i ", "rw");
-    if (!ffmpeg) return -1;
-    printf("hello world\n");
-    pclose(ffmpeg);
     return 0;
-}
+}