audio: move direct packet reading from decoders to common code

Another bit of preparation.

audio/decode/ad.h

@@ -35,7 +35,8 @@ struct ad_functions {
     int (*init)(struct dec_audio *da, const char *decoder);
     void (*uninit)(struct dec_audio *da);
     int (*control)(struct dec_audio *da, int cmd, void *arg);
-    int (*decode_packet)(struct dec_audio *da, struct mp_audio **out);
+    int (*decode_packet)(struct dec_audio *da, struct demux_packet *pkt,
+                         struct mp_audio **out);
 };
 
 enum ad_ctrl {

audio/decode/ad_lavc.c

@@ -42,7 +42,6 @@ struct priv {
     AVFrame *avframe;
     struct mp_audio frame;
     bool force_channel_map;
-    struct demux_packet *packet;
     uint32_t skip_samples;
 };
 
@@ -165,27 +164,18 @@ static int control(struct dec_audio *da, int cmd, void *arg)
     switch (cmd) {
     case ADCTRL_RESET:
         avcodec_flush_buffers(ctx->avctx);
-        talloc_free(ctx->packet);
-        ctx->packet = NULL;
         ctx->skip_samples = 0;
         return CONTROL_TRUE;
     }
     return CONTROL_UNKNOWN;
 }
 
-static int decode_packet(struct dec_audio *da, struct mp_audio **out)
+static int decode_packet(struct dec_audio *da, struct demux_packet *mpkt,
+                         struct mp_audio **out)
 {
     struct priv *priv = da->priv;
     AVCodecContext *avctx = priv->avctx;
 
-    struct demux_packet *mpkt = priv->packet;
-    if (!mpkt) {
-        if (demux_read_packet_async(da->header, &mpkt) == 0)
-            return AD_WAIT;
-    }
-
-    priv->packet = talloc_steal(priv, mpkt);
-
     int in_len = mpkt ? mpkt->len : 0;
 
     AVPacket pkt;
@@ -203,13 +193,11 @@ static int decode_packet(struct dec_audio *da, struct mp_audio **out)
             mpkt->len    -= ret;
             mpkt->pts = MP_NOPTS_VALUE; // don't reset PTS next time
         }
-        if (mpkt->len == 0 || ret < 0) {
-            talloc_free(mpkt);
-            priv->packet = NULL;
-        }
         // LATM may need many packets to find mux info
-        if (ret == AVERROR(EAGAIN))
+        if (ret == AVERROR(EAGAIN)) {
+            mpkt->len = 0;
             return AD_OK;
+        }
     }
     if (ret < 0) {
         MP_ERR(da, "Error decoding audio.\n");

audio/decode/ad_spdif.c

@@ -242,16 +242,13 @@ fail:
     return -1;
 }
 
-static int decode_packet(struct dec_audio *da, struct mp_audio **out)
+static int decode_packet(struct dec_audio *da, struct demux_packet *mpkt,
+                         struct mp_audio **out)
 {
     struct spdifContext *spdif_ctx = da->priv;
 
     spdif_ctx->out_buffer_len  = 0;
 
-    struct demux_packet *mpkt;
-    if (demux_read_packet_async(da->header, &mpkt) == 0)
-        return AD_WAIT;
-
     if (!mpkt)
         return AD_EOF;
 
@@ -259,13 +256,13 @@ static int decode_packet(struct dec_audio *da, struct mp_audio **out)
 
     AVPacket pkt;
     mp_set_av_packet(&pkt, mpkt, NULL);
+    mpkt->len = 0; // will be fully consumed
     pkt.pts = pkt.dts = 0;
     if (!spdif_ctx->lavf_ctx) {
         if (init_filter(da, &pkt) < 0)
             return AD_ERR;
     }
     int ret = av_write_frame(spdif_ctx->lavf_ctx, &pkt);
-    talloc_free(mpkt);
     avio_flush(spdif_ctx->lavf_ctx->pb);
     if (ret < 0)
         return AD_ERR;

audio/decode/dec_audio.c

@@ -161,13 +161,23 @@ void audio_uninit(struct dec_audio *d_audio)
     uninit_decoder(d_audio);
     af_destroy(d_audio->afilter);
     talloc_free(d_audio->waiting);
+    talloc_free(d_audio->packet);
     talloc_free(d_audio);
 }
 
 static int decode_new_frame(struct dec_audio *da)
 {
     while (!da->waiting) {
-        int ret = da->ad_driver->decode_packet(da, &da->waiting);
+        if (!da->packet) {
+            if (demux_read_packet_async(da->header, &da->packet) == 0)
+                return AD_WAIT;
+        }
+
+        int ret = da->ad_driver->decode_packet(da, da->packet, &da->waiting);
+        if (ret < 0 || (da->packet && da->packet->len == 0)) {
+            talloc_free(da->packet);
+            da->packet = NULL;
+        }
         if (ret < 0)
             return ret;
 
@@ -285,8 +295,8 @@ void audio_reset_decoding(struct dec_audio *d_audio)
     d_audio->pts = MP_NOPTS_VALUE;
     d_audio->pts_offset = 0;
     d_audio->pts_reset = false;
-    if (d_audio->waiting) {
-        talloc_free(d_audio->waiting);
-        d_audio->waiting = NULL;
-    }
+    talloc_free(d_audio->waiting);
+    d_audio->waiting = NULL;
+    talloc_free(d_audio->packet);
+    d_audio->packet = NULL;
 }

audio/decode/dec_audio.h

@@ -48,6 +48,8 @@ struct dec_audio {
     bool pts_reset;
     // For free use by the ad_driver
     void *priv;
+    // Strictly internal to dec_audio.c
+    struct demux_packet *packet;
 };
 
 enum {