static int ffmmal_read_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame) { MMALDecodeContext *ctx = avctx->priv_data; MMAL_BUFFER_HEADER_T *buffer = NULL; MMAL_STATUS_T status = 0; int ret = 0; if (ctx->eos_received) goto done; while (1) { // To ensure decoding in lockstep with a constant delay between fed packets // and output frames, we always wait until an output buffer is available. // Except during start we don't know after how many input packets the decoder // is going to return the first buffer, and we can't distinguish decoder // being busy from decoder waiting for input. So just poll at the start and // keep feeding new data to the buffer. // We are pretty sure the decoder will produce output if we sent more input // frames than what a h264 decoder could logically delay. This avoids too // excessive buffering. // We also wait if we sent eos, but didn't receive it yet (think of decoding // stream with a very low number of frames). if (ctx->frames_output || ctx->packets_sent > MAX_DELAYED_FRAMES || ctx->eos_sent) { buffer = mmal_queue_wait(ctx->queue_decoded_frames); } else { buffer = mmal_queue_get(ctx->queue_decoded_frames); } if (!buffer) goto done; ctx->eos_received |= !!(buffer->flags & MMAL_BUFFER_HEADER_FLAG_EOS); if (ctx->eos_received) goto done; if (buffer->cmd == MMAL_EVENT_FORMAT_CHANGED) { MMAL_COMPONENT_T *decoder = ctx->decoder; MMAL_EVENT_FORMAT_CHANGED_T *ev = mmal_event_format_changed_get(buffer); MMAL_BUFFER_HEADER_T *stale_buffer; av_log(avctx, AV_LOG_INFO, "Changing output format.\n"); if ((status = mmal_port_disable(decoder->output[0]))) goto done; while ((stale_buffer = mmal_queue_get(ctx->queue_decoded_frames))) mmal_buffer_header_release(stale_buffer); mmal_format_copy(decoder->output[0]->format, ev->format); if ((ret = ffmal_update_format(avctx)) < 0) goto done; if ((status = mmal_port_enable(decoder->output[0], output_callback))) goto done; if ((ret = ffmmal_fill_output_port(avctx)) < 0) goto done; if ((ret = ffmmal_fill_input_port(avctx)) < 0) goto done; mmal_buffer_header_release(buffer); continue; } else if (buffer->cmd) { char s[20]; av_get_codec_tag_string(s, sizeof(s), buffer->cmd); av_log(avctx, AV_LOG_WARNING, "Unknown MMAL event %s on output port\n", s); goto done; } else if (buffer->length == 0) { // Unused output buffer that got drained after format change. mmal_buffer_header_release(buffer); continue; } ctx->frames_output++; if ((ret = ffmal_copy_frame(avctx, frame, buffer)) < 0) goto done; *got_frame = 1; break; } done: if (buffer) mmal_buffer_header_release(buffer); if (status && ret >= 0) ret = AVERROR_UNKNOWN; return ret; }
static int ffmmal_read_frame(AVCodecContext *avctx, AVFrame *frame, int *got_frame) { MMALDecodeContext *ctx = avctx->priv_data; MMAL_BUFFER_HEADER_T *buffer = NULL; MMAL_STATUS_T status = 0; int ret = 0; if (ctx->eos_received) goto done; while (1) {  