avfilter/asubprocess: add checks for subprocess output (should be wav)

Signed-off-by: Stefan Westerfeld <stefan@space.twc.de>

libavfilter/af_asubprocess.c

@@ -486,14 +486,20 @@ static int write_frame(AVFilterContext *ctx, ASubProcessContext *s, AVFilterLink
     return ret;
 }
 
-static int try_read_frame(ASubProcessContext *s, AVFilterLink *outlink)
+static int try_read_frame(AVFilterContext *ctx)
 {
+    AVFilterLink *outlink = ctx->outputs[0];
+    ASubProcessContext *s = ctx->priv;
     int ret;
 
     if (s->state == STATE_EXPECT_RIFF && sp_can_read(s->sp) >= 12)
     {
         char buffer[12];
         sp_read(s->sp, buffer, 12);
+        if ((memcmp (buffer, "RIFF", 4) && memcmp (buffer, "RF64", 4)) || memcmp (buffer + 8, "WAVE", 4)) {
+            av_log(ctx, AV_LOG_ERROR, "Subprocess output is not a valid wav file.\n");
+            return AVERROR_INVALIDDATA;
+        }
         s->state = STATE_EXPECT_CHUNK;
     }
     if (s->state == STATE_EXPECT_CHUNK && sp_can_read(s->sp) >= 8)
@@ -501,9 +507,9 @@ static int try_read_frame(ASubProcessContext *s, AVFilterLink *outlink)
         unsigned char x[8];
         sp_read(s->sp, x, 8);
         s->chunk_size = AV_RL32 (x + 4);
-        if (x[0] == 'd' && x[1] == 'a' && x[2] == 't' && x[3] == 'a')
+        if (!memcmp (x, "data", 4))
             s->state = STATE_IN_DATA_CHUNK;
-        else if (x[0] == 'f' && x[1] == 'm' && x[2] == 't' && x[3] == ' ' && s->chunk_size >= 16)
+        else if (!memcmp (x, "fmt ", 4) && s->chunk_size >= 16)
             s->state = STATE_IN_FMT_CHUNK;
         else
             s->state = STATE_SKIP_CHUNK;
@@ -511,8 +517,35 @@ static int try_read_frame(ASubProcessContext *s, AVFilterLink *outlink)
     if (s->state == STATE_IN_FMT_CHUNK && sp_can_read(s->sp) >= 16)
     {
         unsigned char data[16];
+        int format, nb_channels, sample_rate;
         sp_read(s->sp, data, 16);
-        s->out_bit_depth = AV_RL16 (data + 14);
+
+        format           = AV_RL16(data);
+        nb_channels      = AV_RL16(data + 2);
+        sample_rate      = AV_RL32(data + 4);
+        s->out_bit_depth = AV_RL16(data + 14);
+
+        if (format != 1 && format != 0xFFFE) { // TODO: check extensible wav format: should be PCM
+            av_log(ctx, AV_LOG_ERROR,
+                   "Unsupported wav format (%d) from subprocess (expected PCM).\n", format);
+            return AVERROR_INVALIDDATA;
+        }
+        if (nb_channels != outlink->ch_layout.nb_channels) {
+            av_log(ctx, AV_LOG_ERROR,
+                   "Number of output channels (%d) from subprocess doesn't match input channels (%d).\n",
+                   nb_channels, outlink->ch_layout.nb_channels);
+            return AVERROR_INVALIDDATA;
+        }
+        if (sample_rate != outlink->sample_rate) {
+            av_log(ctx, AV_LOG_ERROR,
+                   "Sample rate (%d) from subprocess doesn't match input sample rate (%d).\n",
+                   sample_rate, outlink->sample_rate);
+            return AVERROR_INVALIDDATA;
+        }
+        if (s->out_bit_depth != 8 && s->out_bit_depth != 16 && s->out_bit_depth != 24 && s->out_bit_depth != 32) {
+            av_log(ctx, AV_LOG_ERROR, "Unsupported output wav bit depth (%d) from subprocess.\n", s->out_bit_depth);
+            return AVERROR_INVALIDDATA;
+        }
         s->chunk_size -= 16;
         s->state = STATE_SKIP_CHUNK;
     }
@@ -560,7 +593,7 @@ static int activate(AVFilterContext *ctx)
 
     FF_FILTER_FORWARD_STATUS_BACK(outlink, inlink);
 
-    ret = try_read_frame(s, outlink);
+    ret = try_read_frame(ctx);
     if (ret != 0)
         return ret;
     ret = ff_inlink_consume_frame(inlink, &in);
@@ -588,11 +621,15 @@ static int activate(AVFilterContext *ctx)
                 return ret;
         }
     }
-    ret = try_read_frame(s, outlink);
+    ret = try_read_frame(ctx);
     if (ret != 0)
         return ret;
 
     if (s->eof) {
+        if (s->state != STATE_IN_DATA_CHUNK) {
+            av_log(ctx, AV_LOG_ERROR, "Subprocess output wav is incomplete (no data chunk found)\n");
+            return AVERROR_INVALIDDATA;
+        }
         // s->last_pts
         ff_outlink_set_status(outlink, AVERROR_EOF, AV_NOPTS_VALUE);
         return 0;